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Histiocytoses
Langerhans Cell Histiocytoses
• Langerhans cells have Birbeck granules by electron microscopy.
• Common in children ages 1–3 years, but can occur at any age.
• Traditionally classified into the following categories but they exist along a clinical spectrum.
Letterer–Siwe Disease (Multifocal, Multisystem)
• Multisystem involvement (skin, lung, liver, lymph nodes, bone, bone marrow).
• Classically in those <1–2 year(s) of age.
• Favors scalp, flexural neck, axilla, perineum, trunk (Fig. 76.1).
Fig. 76.1 Langerhans cell histiocytosis – clinical spectrum. A Scalp involvement may initially be diagnosed as seborrheic dermatitis; however, there are usually more discrete papules and crusting. B Pink, thin plaques with fissuring along the inguinal crease can also resemble seborrheic dermatitis. C Advanced disease with coalescence of papules into large plaques and prominent inguinal lymphadenopathy. D The presence of petechiae and purpuric papules is a clue to the diagnosis. E In an adult, the clinical presentation of inguinal involvement is similar to that of infants. F In patients with darkly pigmented skin, the papules can be hypopigmented. B, Courtesy, Richard Antaya, MD; D, F, Courtesy, Julie V. Schaffer, MD.
• Secondary changes include scale, crusts, petechiae/purpura.
Hand–Schüller–Christian Disease
Eosinophilic Granuloma (Unifocal)
• Localized variant (Fig. 76.2).
Fig. 76.2 Langerhans cell histiocytosis (eosinophilic granuloma of the bone). Radiography of the femur shows a large well-circumscribed osteolytic lesion. Courtesy, Edward McCarthy, MD.
• Classically in children, ages 7–12 years.
