HEAD AND NECK PATHOLOGY

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CHAPTER 3 HEAD AND NECK PATHOLOGY

Malignant peripheral nerve sheath tumor
Olfactory neuroblastoma (esthesioneuroblastoma)
Melanotic neuroectodermal tumor of infancy
Ectomesenchymoma
Nasal glial heterotopia
Nasopharyngeal carcinoma
Nasal / choanal polyps
Hairy polyp of the nasopharynx
Salivary gland anlage tumor (congenital pleomorphic adenoma)
Chondromesenchymal hamartoma
(Juvenile) nasopharyngeal angiofibroma
Juvenile laryngeal papillomatosis
Laryngeal hemangioma
Laryngeal granular cell tumour
Cholesteatoma

Thyroid disorders

Thyroid carcinoma (excluding medullary carcinoma)
Papillary carcinoma of thyroid
Follicular carcinoma of thyroid
Medullary thyroid carcinoma
Thyroid c-cell hyperplasia
Spindle cell tumor with thymus-like differentiation (SETTLE)

Oral lesions

Ectomesenchymal chondromyxoid tumor of the anterior tongue
Focal oral mucinosis
Congenital granular cell epulis (granular cell tumor)
Salivary gland tumors

Pleomorphic adenoma
Acinic cell carcinoma
Mucoepidermoid carcinoma
Adenoid cystic carcinoma
Sialoblastoma
Salivary gland hemangioma
Odontogenic tumors

Other lesions

Ossifying fibroma
Central giant cell lesion
Dermoid cyst
Branchial cleft remnants
Thyroglossal duct remnants

INTRODUCTION

• Many head and neck lesions are covered elsewhere in other sections, such as soft tissue tumors
• Detailed here are only entities either specific to, or much more common in, this area, or in which there are specific issues when such entities occur in the head and neck

MALIGNANT PERIPHERAL NERVE SHEATH TUMOR

Epidemiology

• Usually NF1 associated when occurs in childhood
• In patients with NF-1

image MPNST diagnosed in childhood at average age 12 years

– can rarely occur in infancy (Friedrich et al 2007)

Clinical features

• Solid infiltrative lesion
• Presentation according to site
• MPNST arising from enlarging plexiform neurofibromas

image present with pain / neurological impairment

Histopathological features (Figs 3.1–3.3)

• Spindle (majority) and/or epithelioid variants
• Plump fusiform cells
• Variably cellular
• <5% MPNST may show perineurial differentiation

image long slender processes

– EMA+, S100−

image better prognosis, less associated with NF-1 (Hirose et al 1998)

image

Fig 3.1 Photograph of a case of malignant peripheral nerve sheath tumor in an adolescent with known neurofibromatosis.

image

Fig. 3.2

image

Figs 3.2–3.3 Photomicrographs of a case of malignant peripheral nerve sheath tumor in an adolescent with known neurofibromatosis, demonstrating an infiltrative spindle cell lesion, which focally expressed neural markers.

Immunohistochemical staining

• Focal S100+
• Focal GFAP / PGP+

Differential diagnoses and pitfalls

• Cellular Schwannoma may look similar but:

image diffuse S100+
image encapsulated

OLFACTORY NEUROBLASTOMA (ESTHESIONEUROBLASTOMA)

Epidemiology

• Peak in 2nd decade in childhood but all ages

Clinical features

• Nasal obstruction and/or epistaxis

Histopathological features (Figs 3.4, 3.5)

• Lobules and nests of tumor cells within a vascular stroma
• Nests of uniform round to ovoid cells

image neurofibrillary matrix
image neural rosettes

• Grade I (well differentiated) – grade IV (undifferentiated / anaplastic)
image

Fig. 3.4

image

Figs 3.4–3.5 Photomicrographs of a case of olfactory neuroblastoma, showing monotonous nests and sheets of uniform ovoid cells in a subepithelial location.

Immunohistochemical staining

• NSE+ tumor cells (± chromogranin, synaptophysin etc)
• S100+ peripheral sustentacular cells
• CK, CD99−

Electron microscopy

• Dense core neurosecretory granules

Differential diagnoses and pitfalls

• Olfactory neuroblastomas lack the EWS/FLI1 fusion and are genetically unrelated to PNET
• However, PNET may also rarely occur as primary sinonasal tumor (Kumar et al 1999)

MELANOTIC NEUROECTODERMAL TUMOR OF INFANCY

Epidemiology

• Infants

Clinical features

• Majority (90%) in craniofacial region

image especially maxilla

• Pigmented enlarging mass
• VMA elevated in a minority
• 5% metastases
• Local recurrence in one-third (Fowler et al 2006)

Histopathological features (Figs 3.6–3.11)

• Poorly circumscribed infiltrative and unencapsulated lesion
• Dual population of cell types

image large epithelioid pigmented cells

– CK, HMB45+

image small neuroblast like cells

– NSE, CD56+

image variably collagenous fibrous stroma

• No reliable histopathological or molecular features to predict the biological behavior in individual cases (Fowler et al 2006)
image

Fig 3.6 Photograph of a case of melanotic neuroectodermal tumor of infancy, demonstrating an intraosseous lesion with areas of black (melanin) pigmentation seen on macroscopic examination.

image

Fig. 3.7

image

Fig. 3.8

image

Fig. 3.9

image

Figs 3.7–3.10 Photomicrographs of cases of melanotic neuroectodermal tumor of infancy, demonstrating an infiltrative lesion composed of a dual population of cells within a fibrous stroma; large, epithelioid pigmented melanocyte-like cells and smaller nests of neuroblastoma-like cells.

image

Fig 3.11 Photomicrograph of a case of melanotic neuroectodermal tumor of infancy, demonstrating the larger cells to immunostain with HMB45.

Differential diagnoses and pitfalls

• Core needle biopsy may demonstrate only the small cell component!

image clinicopathological correlation required in this setting

ECTOMESENCHYMOMA

• Tumor derived from pluripotent primitive neural crest cells with mixed pathways of differentiation

Epidemiology

• Usually young children, including infants

Clinical features

• Local mass lesion, usually head and neck or pelvis or perineum
• Behavior essentially as RMS

Histopathological features

• Admixed neural and other mesenchymal tissues:

image mesenchymal elements usually eRMS (Mouton et al 1996)
image admixed neural elements

– neuroblasts
– ganglion cells
– melanocytes

• Neural tissue usually neuroblastic differentiation with ganglion cells in an otherwise classic embryonal rhabdomyosarcoma

Immunohistochemical staining

• Focal expression of neural and other mesenchymal markers

Differential diagnoses and pitfalls

• May histologically appear as rhabdomyosarcoma with focal neural areas
• May only show neural elements in recurrence or metastasis of ‘RMS’ (Sebire et al 2003, Floris et al 2007)
• Microarray analyses shows clustering most closely with MPNST (Kleinschmidt-DeMasters et al 2007)

NASAL GLIAL HETEROTOPIA

Epidemiology

• Birth or first few years of life

Clinical features

• Nasal / paranasal mass

image nasal cavity – majority
image nasal bridge (Penner & Thompson 2003)

• Rarely sinuses or parapharyngeal sites
• No intracranial component or bony defect
• May also occur in nasopharynx and may rarely be associated with facial clefts

Histopathological features (Figs 3.12–3.14)

• Unencapsulated lesion composed of:

image islands of astrocytes and neuroglial fibers
image admixed with variable amounts of fibrovascular connective tissue stroma

• Glial component may be subtle in some cases on initial H&E staining

image glial fibrillary acidic protein (GFAP) staining diagnostic

image

Fig. 3.12

image

Figs 3.12–3.13 Photomicrographs of a case of nasal glial heterotopia, demonstrating an unencapsulated lesion composed of islands of astrocytes and neuroglial fibers admixed with variable amounts of fibrovascular connective tissue stroma.

image

Fig 3.14 Photomicrograph of a case of nasal glial heterotopia, demonstrating strong glial positivity on immunostaining for GFAP.

Immunohistochemical staining

• GFAP+

Differential diagnoses and pitfalls

• Encephalocele

image communicates with an intracranial component via a bony defect

NASOPHARYNGEAL CARCINOMA

Epidemiology

• Usually males 40–60 years of East Asian origin

image occurs rarely but is well-reported in childhood

• Most are EBV-related

Clinical features

• Local disease

image nasal obstruction / discharge
image Eustachian tube blockage

• Metastatic disease
• >80% overall survival in this age group (Cannon et al 2006)

Histopathological features

• Several histological subtypes

image nonkeratinizing

– nests and syncytial like sheets of squamoid / epithelioid cells in lymphoid-rich stroma
– undifferentiated subtype

· large cells with vesicular nuclei and prominent nucleoli

image keratinizing

– nests of cells with morphology of invasive squamous cell carcinoma

Immunohistochemical staining

• MNF116 and p63 uniform positivity
• EBER + ISH

image almost all EBER+ in non-keratinizing subtype
image focal EBER+ in keratinizing subtype

• c-Kit (CD117)+ in 90% (Bar-Sela et al 2005)
• Heparanase expression inversely associated with survival (Bar-Sela et al 2005)
• Stromal CD10 expression

image associated with adverse prognosis (Braham et al 2006)

Differential diagnoses and pitfalls

• Amount of lymphoid stroma may vary from almost none to extensive

image can mimic lymphoma

• Most childhood cases are nonkeratinizing type

NASAL / CHOANAL POLYPS

• May occur but generally rare in childhood

image if present, consider underlying conditions:

– Kartagener’s syndrome
– cystic fibrosis (CF)

• Polypoid lesions (Fig 3.15)

image covered by respiratory epithelium
image underlying edematous stroma
image thickened basement membrane
image mixed inflammatory cell infiltrate, including eosinophils
• Polyps in CF

image may be complicated by fungal infection
image show dilated glands containing eosinophilic inspissated material
image less eosinophils and basement membrane thickening than allergic type

image

Fig 3.15 Photomicrograph of a case of an inflammatory / allergic nasal polyp in a child with cystic fibrosis. The polyp is covered by respiratory epithelium with underlying edematous stroma containing a mixed inflammatory infiltrate, and there is a dilated gland containing eosinophilic inspissated material.

HAIRY POLYP OF THE NASOPHARYNX

• Infants
• F > M
• Mass affecting nasopharynx, palate or middle ear (Kieff et al 1998, Chang et al 2007)

image also rarely reported in association with facial cleft
• Polypoid lesion covered with skin (Fig 3.16)

image contains pilosebaceous units
• Fibrofatty core

image may contain cartilage, bone or muscle

• No elements from other germ cell layers cf true teratoma
image

Fig 3.16 Photomicrograph of a hairy polyp of the nasopharynx, demonstrating a fibrofatty core, in this case also containing cartilage, covered by skin with end-all structures.

SALIVARY GLAND ANLAGE TUMOR (CONGENITAL PLEOMORPHIC ADENOMA)

• Infants, usually present at birth
• M > F
• Benign

image curative excision

• Midline polypoid lesion

image nonkeratinizing squamous epithelium
image stroma with nodules of fusiform cells
image tubule formation
image ducts

• Bland nuclei
• Vimentin, CK and SMA+

CHONDROMESENCHYMAL HAMARTOMA

• Intranasal mass in an infant
• Two histological elements:

image myxoid to spindle cell stroma
image nodules of mature cartilage

(JUVENILE) NASOPHARYNGEAL ANGIOFIBROMA

Epidemiology

• Males
• First three decades

image peak in second decade

• Exclude testicular feminization syndrome if occurs in a phenotypically female patient
• Most are sporadic

image increased frequency in patients with familial adenomatous polyposis

Clinical features

• Nasopharyngeal mass with local infiltration

image extensive involvement in one-third

• Nasal obstruction
• Epistaxis
• Other local symptoms
• 20% local recurrence

Histopathological features (Figs 3.17–3.21)

• Numerous predominantly thin-walled vessels

image bland endothelium

• Variably fibrous stroma

image plump spindle to stellate cells

• Lesions become increasingly fibrotic and less vascular with maturity
• Therapeutic embolization may be associated with secondary changes
image

Fig. 3.17

image

Fig. 3.18

image

Figs 3.17–3.19 Photomicrographs of cases of juvenile nasopharyngeal angiofibromas, demonstrating a variably fibrous and cellular stroma containing plump ovoid cells, with numerous thin walled vessels. The degree of vascularity and cellularity may vary with age and therapy effects.

image

Fig. 3.20

image

Figs 3.20–3.21 Photomicrographs of cases of juvenile nasopharyngeal angiofibromas which had been previously treated by vascular embolization prior to surgery, demonstrating presence of foreign material in vessels with focal foreign-body type reaction.

Immunohistochemical staining

• Positive stromal and endothelial nuclear immunostaining for androgen receptors in 75% (Hwang et al 1998)
• Diffuse nuclear expression of beta-catenin in stromal cells

image activating beta-catenin gene mutations in 75% (Abraham et al 2001)

• Most also express VEGF (Saylam et al 2006)

JUVENILE LARYNGEAL PAPILLOMATOSIS

Epidemiology

• HPV related lesions

image especially types 6 and 11
image types 11 and 16 associated with a more aggressive course

• Presents during the first 5 years of life

image vertically transmitted

– first born
– vaginal delivery
– young mother

• Affects around 1% of children born to mothers with vaginal condyloma

Clinical features

• Multiple laryngeal papillomatous lesions

image extralaryngeal spread also occurs in 30%

– bronchial / pulmonary involvement in 5%
– rare esophageal involvement

• Growth and recurrences
• 5–15% mortality
• Complications

image infection
image asphyxia
image secondary pulmonary complications
image malignant transformation to squamous cell carcinoma (rare)

• HPV-11 especially associated with more severe disease including tracheal involvement and pulmonary disease (Wiatrak et al 2004)
• Local management with minimal iatrogenic morbidity is required

Histopathological features (Figs 3.22, 3.23)

• Papillomatous lesions covered by non-keratinizing squamous epithelium

image ± koilocytosis
image ± dyskeratosis

• Usually no pleomorphism
• Malignant transformation to squamous cell carcinoma may occur
image

Fig. 3.22

image

Figs 3.22–3.23 Photomicrographs of cases of juvenile laryngeal papillomatosis, demonstrating squamous cell papillomata with no cytological atypia and variable mild inflammation.

Differential diagnoses and pitfalls

• Relevance of minor ‘dysplasia’-like changes in otherwise typical childhood cases is unknown

LARYNGEAL HEMANGIOMA

• Usually capillary-type
• <50% of patients have associated cutaneous hemangiomas
• No cytological atypia
• GLUT1 positive or negative according to subtype

LARYNGEAL GRANULAR CELL TUMOUR

• Sheets of large polygonal cells with granular cytoplasm

image DPAS+
image S100+
image CD68+

A range of other tumors may also rarely affect the larynx (see other sections) (Fig 3.24)

image

Fig 3.24 Photomicrograph of a case of laryngeal paraganglioma in a child.

CHOLESTEATOMA

Epidemiology

• Children
• Most associated with otitis media and perforation of tympanic membrane
• ‘Congenital cholesteatoma’

image younger children

– including infants

image intact membrane
image no preceding history of middle ear infection
image pearly white mass medial to the tympanic membrane
image probably resulting from abnormal epithelial rests (Kazahaya & Ptsic 2004)

• Histologically benign but locally destructive

Clinical features

• Mass and ear discharge

Histopathological features

• Fragments of keratin and squamous cells
• Keratinizing squamous epithelium

image no atypia

• Stromal matrix

Differential diagnoses and pitfalls

• Squamous epithelium in appropriate site required for confirmation of cholesteatoma

image not just keratin and foreign body reaction

• Cholesterol granuloma
• Foreign body giant cell / histiocytic reaction in middle ear

image associated with chronic otitis media

THYROID DISORDERS

• Differential diagnosis of goitre in childhood:

image congenital hypothyroidism due to dyshormonogenesis
image thyroid hemiagenesis
image thyroglossal duct cyst
image simple goitre
image cystic lesions
image nodular hyperplasia
image follicular adenoma
image Graves’ disease
image Hashimoto thyroiditis
image Carcinoma

THYROID CARCINOMA (EXCLUDING MEDULLARY CARCINOMA)

• Children with thyroid carcinoma:

image tend to present with more advanced disease than adults

– lymph node and lung metastases

image have higher recurrence rates but better overall survival

Epidemiology

• Mainly adults

image rare but well-reported in childhood

– especially papillary carcinoma

image increased rate with radiation exposure

PAPILLARY CARCINOMA OF THYROID

Genetics

• RET/PTC rearrangements in >50% in children

Clinical features

• >95% 5-year survival
• Thyroid nodule / mass lesion

Histopathological features (Figs 3.25–3.31)

• Irregular mass lesion within thyroid

image rarely at ectopic sites

• Usually solid
• Unencapsulated so may appear multifocal
• Lymphatic spread
• Rare metastasis outside LN

image usually lung in diffuse sclerosing variant

• Follicular architecture with characteristic nuclei

image enlarged, oval
image optically clear or ground glass
image overlapping
image nuclear grooves

• Variable areas of papillary architecture

image central stromal core
image same nuclear features of covering epithelium

• Psammoma body formation

image concentric lamination, calcified

image

Fig. 3.25

image

Fig. 3.26

image

Fig. 3.27

image

Figs 3.25–3.28 Photomicrographs of cases of childhood papillary carcinoma, demonstrating cystic and papillary architecture with epithelial cells showing overlapping nuclei and nuclear grooves, and psammoma body formation.

image

Fig. 3.29

image

Fig. 3.30

image

Figs 3.29–3.31 Photomicrographs of cases of childhood papillary carcinoma, which may show local infiltration, lymph node spread and even more widespread metastatic disease, most commonly to lung.

Recognized variants

• Follicular

image mainly follicular architecture with no papillary areas
image classical papillary carcinoma nuclear features

• Macrofollicular

image large follicles
image multinodular goitre-like on low power

• Oncocytic

image prominent areas of oncocytic cells but similar nuclear features

• Clear cell

image prominent clear cells areas but similar nuclear features

• Diffuse sclerosing

image relatively more common in children

– diffuse thyroidal involvement
– stromal fibrosis

image lung metastases in 25%

• Tall cell

image cells at least 3 times taller than width

• Columnar

image pseudostratified cells with hyperchromatic nuclei

• Solid

image relatively more common in children
image sheets of cells with classical nuclear features
image local invasion

• Microcarcinoma

image <1cm
image often incidental finding in adults

– in children may metastasize

Immunohistochemical staining

• Cytokeratin+
• Thyroglobulin+
• TTF-1+
• Ck19+
• Chromogranin−

FOLLICULAR CARCINOMA OF THYROID

Clinical features

• Mainly adults

image rare in children

• Thyroidal mass lesion

Histopathological features

• Mass lesion within thyroid
• Usually solid
• Encapsulated or infiltrating
• Vascular and lymphatic spread
• Follicular architecture without characteristic nuclei of papillary carcinoma
• Nuclei usually round / ovoid and bland

image nuclear atypia does not necessarily relate to aggressive behavior

Recognized variants

• Minimally invasive and widely invasive:

image depending on extent of:

– capsular invasion
– vascular invasion (beyond capsule)

• Oncocytic
• Clear cell

Immunohistochemical staining

• Cytokeratin+
• Thyroglobulin+
• TTF-1+
• Ck19+
• Bcl2+
• Beta catenin+
• Chromogranin−

Other types of carcinoma of thyroid

• Poorly differentiated, anaplastic, squamous, mucoepidermoid, and mucinous carcinomas

image usually affect adults

MEDULLARY THYROID CARCINOMA

Epidemiology

• Mainly adults when sporadic
• Children affected when associated with MEN 2A, 2B and familial medullary thyroid carcinoma syndromes

image may even present in infancy in these syndromes

Genetics

• RET germline mutations with multiple endocrine neoplasia (MEN) syndromes

Clinical features

• May have other MEN 2 features
• Painless thyroid mass
• 50% with node metastases at presentation
• 15% with distant metastases at presentation
• Raised serum calcitonin levels
• May present with other unusual endocrine paraneoplastic features also

Histopathological features (Figs 3.32, 3.33)

• Irregular unencapsulated firm mass centrally in thyroid lobe
• Usually unicentric

image except syndromic cases

• Solid sheets, nests or trabeculae of tumor cells composed of varying proportions of:

image polygonal, round or spindle cells

– round / oval bland nuclei

· occasionally pleomorphic

– rare mitoses
– locally infiltrative

image fibrovascular intervening stroma

– variable appearance
– may be hyalinized
– majority have amyloid areas

· Congo red positive

image

Fig. 3.32

image

Figs 3.32–3.33 Photomicrographs of a case of medullary carcinoma of thyroid (microcarcinoma) in a child with MENII, demonstrating a small unencapsulated, infiltrating lesion with interstitial round to polygonal cells and variable fibrosis, tumor cells showing calcitonin positivity on immunostaining.

Immunohistochemical staining

• CEA+

image strong expression associated with worse prognosis

• Calcitonin+
• Chromogranin+
• Synaptophysin+
• TTF-1+
• ±S100 + sustentacular cells peripherally

Differential diagnoses and pitfalls

• MEN associated cases

image younger age
image multicentric
image bilateral

THYROID C-CELL HYPERPLASIA

• Precursor of medullary carcinoma of thyroid in familial / inherited forms of medullary carcinoma of thyroid
• Groups of interfollicular C-cells

image focal
image nodular
image diffuse

• Multiple clusters of more than 6 C-cells or >50 C-cells / low power field
• Calcitonin / chromogranin+
• Difficult distinction in some cases from microinvasive medullary carcinoma

SPINDLE CELL TUMOR WITH THYMUS-LIKE DIFFERENTIATION (SETTLE)

• Children and young adults
• M > F
• Painless thyroid mass
• Metastases in >50%

image late metastases well-reported

• Lobulated pattern
• Fascicles of spindle cells merging with tubular / glandular structures
• Strong cytokeratin expression in all components

ORAL LESIONS

• Oral tumors are rare in childhood
• Main groups of lesions are salivary gland or tooth apparatus related
• includes parotitis

– bacterial or viral (Fig 3.34)

• Consider underlying syndromes such as Li–Fraumeni if squamous cell carcinoma occurs in this age group
image

Fig 3.34 Photomicrograph of a case of CMV parotitis, demonstrating inflammation associated with epithelial viral inclusions, confirmed as CMV on immunostaining (inset).

ECTOMESENCHYMAL CHONDROMYXOID TUMOR OF THE ANTERIOR TONGUE

• Rare, affects all ages including children
• Slow growing well-circumscribed nodule on the anterior dorsum of tongue
• Composed of

image uniform round, polygonal or spindled cells
image myxoid matrix alcian blue+
image GFAP+

FOCAL ORAL MUCINOSIS

• Rare, affects all ages including children
• Painless nodule in the mouth
• Well circumscribed myxoid lesion

image stellate fibroblasts
image fibrillar extensions

CONGENITAL GRANULAR CELL EPULIS (GRANULAR CELL TUMOR)

• Congenital oral lesion
• F > M
• Affects maxilla / mandible
• Usually firm midline nodule on the alveolar ridge
• Composed of (Fig 3.35)

image large cells with eosinophilic granular cytoplasm
image no atypia
image prominent vascular pattern
• Vimentin+
• S100−
image

Fig 3.35 Photomicrograph of a case of congenital granular cell tumor (epulis), demonstrating numerous large cells with eosinophilic granular cytoplasm.

SALIVARY GLAND TUMORS

Epidemiology

• Mainly adults but well reported in children

image in pediatric practice, epithelial and mesenchymal tumors are of similar frequency compared to more epithelial in adults
image benign and malignant lesions similar frequency
image histopathological features as for standard adult cases

– only brief details provided in this section

• Main salivary gland neoplasms in childhood are:

image pleomorphic adenoma
image acinic cell carcinoma
image mucoepidermoid carcinoma
image adenoid cystic carcinoma
image sialoblastoma
image hemangioma

• Prognosis related to age, stage and tumor type

Clinical features

• Usually solid enlarging mass lesion

image parotid or other salivary glands

Histopathological features

PLEOMORPHIC ADENOMA

• Commonest salivary neoplasm overall
• Benign but 5–10% recurrence risk
• Well defined but not always encapsulated
• Highly variable morphology but common components:

image capsule

– variable thickness
– almost always focally absent

· especially mucoid lesions

image epithelial elements

– sheets / ductal structures
– cuboidal, basaloid, squamous, spindled, plasmacytoid, clear cell
– bland nuclei

image stromal elements

– myxoid
– chondroid
– hyaline
– fat
– bone

ACINIC CELL CARCINOMA

• Malignant

image 15% metastases
image 35% recurrence

• Solid and cystic areas
• Acinar cell differentiation is characteristic but mixture of cell types:

image acinar cells

– large polygonal basophilic cytoplasm
– DPAS+ granules
– bland round nuclei

image intercalated duct type cells

– smaller cuboidal cells
– bland central nuclei

image vacuolated cells

– clear cytoplasmic vacuoles
– DPAS−

image clear cells

– like acinar cells but clear cytoplasm

image non-specific glandular cells

• Microcystic pattern if intercellular spaces appear
• Follicular pattern
• Thyroid follicle like structures
• ± lymphoid infiltrate
• CK, A1AT+

MUCOEPIDERMOID CARCINOMA

• 95% 5-year survival (Védrine et al 2006)
• Multicystic and solid
• Mixture of cell types, variety of distributions (Fig 3.36)

image squamoid (epidermoid)

– keratinization rare

image mucous cells

– PAS+

image intermediate cells

– cuboidal

image ± oncocytic, clear or columnar cells
• Low, intermediate and high grade according to scoring system
• High grade associated with more:

image anaplasia
image mitoses
image necrosis
image neural invasion
image solid

image

Fig 3.36 Photomicrograph of a case of mucoepidermoid carcinoma, demonstrating admixed areas of infiltrating nests of squamoid and mucinous cells.

ADENOID CYSTIC CARCINOMA

• High rate of local recurrence and associated mortality
• Three main patterns

image tubular

– well-formed ducts and tubules

image cribriform

– cylindroma like with hyaline microcystic spaces

image solid

– sheets of basaloid cells

• Two main cell types

image basaloid / ductal cells
image myoepithelial cells

• Variable amounts of hyalinized / myxoid stroma
• Perineural invasion

SIALOBLASTOMA (Figs 3.37, 3.38)

• Birth and infancy
• Parotid or submandibular mass
• 20% recurrence

image most cured with surgical excision

• Lobular architecture
• Nests of basaloid cells
• Admixed cuboidal epithelial cells
• Ductules
• Solid nests

image focal peripheral pallisading

• Loose intervening stroma
• Myoepithelial cells
• Variable mitotic rate
• S100, Vimentin+
• Mitotic rate and nuclear pleomorphism may increase with time / recurrence (Brandwein et al 1999)
image

Fig. 3.37

image

Figs 3.37–3.38 Photomicrographs of a case of sialoblastoma in an infant, demonstrating nests of basaloid cells within a loose to fibrous intervening stroma.

SALIVARY GLAND HEMANGIOMA (Figs 3.39–3.41)

• Mainly younger children
• F > M
• Parotid gland swelling
• Infiltrating lesion composed of thin walled vessels

image variably cellular
image no atypia
image entrapped ducts

image

Fig. 3.39

image

Figs 3.39–3.40 Photomicrographs of a case of infantile capillary hemangioma infiltrating the salivary gland in an infant, the vascular channels are highlighted by immunostaining for CD34 or GLUT1.

image

Fig 3.41 Photomicrograph of a case of lymphatic malformation involving the salivary gland. Note the infiltration of the gland by thin walled vascular / lymphatic channels, with no atypia.

ODONTOGENIC TUMORS

• Neoplasms derived from tooth forming apparatus

Epidemiology

• Most are relatively rare in routine pediatric surgical practice

image many require specialist dental pathology review

• Most, especially malignant, entities mainly affect older adults

Clinical features

• Swelling in maxillofacial skeleton or tooth bearing mucosa
• ± pain

image especially if rapidly growing or malignant

• ± abnormal mobility of teeth

Histopathological features

• Main lesions encountered in pediatric surgical practice are listed below (includes selected maxillary / mandibular bony lesions):

Squamous odontogenic tumor

• Arises from periodontal ligament
• Islands of well differentiated squamous epithelium
• Fibrous stroma

Adenomatoid odontogenic tumor

• Teenagers
• Slow growing
• May be associated with unerupted teeth
• Solid nodules of cuboidal odontogenic epithelium

image tubular and ductular areas

• Intervening stroma and amorphous eosinophilic material

image amyloid like material

Keratocystic odontogenic tumor (odontogenic keratocyst)

• Usually mandible
• Benign but locally invasive and destructive
• Cystic structures lined by keratinizing squamous epithelium
• Defined pallisaded basal layer
• No atypia cf SCC
• Possibly PTCH loss 9q22

Ameloblastic fibroma

• Branching / anastomosing epithelial strands

image peripheral pallisaded cells
image ameloblastoma-like

• Myxoid stroma with stellate fibroblast-like cells

image embryonic tooth pulp like
image not like ameloblastoma

• Histologically similar to peripheral dental follicle around an unerupted tooth

image radiology shows difference

Ameloblastic fibro-odontoma

• Ameloblastic fibroma with presence of dentin and enamel
• Mainly occurs in children

Odontoma (complex type)

• Common in children
• Connective tissue capsule with strands of odontogenic epithelium
• Disorganized mass of dentin, enamel and cementum like tissues

image if well-formed hamartomatous tooth like structures present = compound odontoma

Odontoameloblastoma

• Unencapsulated nodular lesion
• Cords of odontogenic epithelium

image follicular / plexiform pattern of ameloblastoma

• Myxoid cellular stroma

image formation of mineralized tooth elements

Calcifying cystic odontogenic tumor

• Benign cystic lesion
• Ameloblastoma like lesion with ‘ghost-cell’ areas in cyst wall

Odontogenic myxoma

• Benign but 25% recurrence
• Intraosseous
• Stellate / spindle cells within a myxoid matrix

image long cytoplasmic processes

Cementoblastoma

• Rare, mandible, first molar
• Nodular mass attached to tooth root
• Masses of acellular cementum-like material
• Peripheral columns of osteosarcoma-like unmineralized tissue
• Peripheral fibrous tissue

OSSIFYING FIBROMA

• Expanding bony lesion

image usually mandible

• Variably cellular fibrous tissue
• Bone and cementum-like areas
• Fibrous dysplasia-like appearance

image but well circumscribed cf FD

• Trabecular and psammomatoid variants

CENTRAL GIANT CELL LESION

• Benign osteolytic lesion, mainly mandible
• Vaguely nodular with collagen bands and metaplastic bone
• Spindle fibroblasts
• Fibromyxoid stroma
• Hemorrhage
• Hemosiderin
• Scattered osteoclast-like giant cells
• Histologically indistinguishable from

image cherubism

– autosomal dominant 4p16.3
– bilateral
– expanded bony lesions
– additional perivascular collagen cuffing may be present

Differential diagnoses and pitfalls

• Maxillary / mandibular bony lesions may be complex and specialist referral required

MISCELLANEOUS LESIONS

• Many soft tissue and cutaneous lesions may of course also occur in the head and neck region, the majority of these being covered in the appropriate sections
• Some surgical pathology specimens may be encountered in pediatric practice with specific benign lesions, many of which are developmental, which do not neatly fit into other categories and are therefore detailed below

DERMOID CYST (Fig 3.42)

• Probable developmental invaginations of embryonic skin
• Mainly midline and embryonic lines of fusion (eg lateral orbit, nasal bridge)

image lateral cases also occur

• Epidermal lined cyst with adnexal structures in wall

image may be solid, depending on size and location
image may show florid secondary changes if rupture occurs

image

Fig 3.42 Photomicrograph of nasal dermoid cyst, lined by epidermis, with adnexal structures in the wall.

BRANCHIAL CLEFT REMNANTS (Fig 3.43)

• Developmental anomaly of fusion of branchial clefts and pouches

image most second branchial cleft

• Clinically present as lesions in anterolateral neck

image cyst, sinus, fistula or skin tag

– note: may also rarely occur in midline

• Lined by non-keratinizing squamous or respiratory type epithelium

image most also have lymphoid tissue in wall
image secondary inflammation and fibrosis

image

Fig 3.43 Photomicrograph of branchial cleft sinus, the tract lined by ciliated respiratory-type epithelium in this case.

THYROGLOSSAL DUCT REMNANTS

• Developmental anomaly of the thyroid diverticulum
• Clinically present as mass lesion in anterior midline of neck

image may also rarely occur more laterally

• Cyst or tract, usually in region of hyoid bone
• Lined by variable epithelium:

image columnar to cuboidal

– may be ciliated

image non-keratinizing squamous
image secondary inflammation and fibrosis
image ectopic thyroid follicles identified in a minority (<20%)

REFERENCES

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Bar-Sela G, Kaplan-Cohen V, Ilan N, Vlodavsky I, Ben-Izhak O. Heparanase expression in nasopharyngeal carcinoma inversely correlates with patient survival. Histopathol. 2006;49:188-193.

Braham H, Trimeche M, Ziadi S, et al. CD10 expression by fusiform stromal cells in nasopharyngeal carcinoma correlates with tumor progression. Virchows Arch. 2006;449:220-224.

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Sebire NJ, Ramsay AD, Malone M, Risdon RA. Extensive post treatment ganglioneuromatous differentiation of rhabdomyosarcoma: malignant ectomesenchymoma in an infant. Pediatr Dev Pathol. 2003;6:94-96.

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