Chapter 47 Uncommon malignant tumors of the skin
1. What is an epithelioid sarcoma?
Epithelioid sarcoma is an exceedingly rare high-grade malignancy of unknown lineage with no normal cellular counterpart. The tumor has an indolent course but a high potential to metastasize. It is remarkable for being a difficult diagnosis, both clinically and histologically, resulting in a high frequency of initial misdiagnosis. Diagnosis is reached on average 8 years after initial clinical presentation.
3. How does epithelioid sarcoma present?
It presents as a painless, firm, slow-growing, intradermal or subcutaneous nodule, often ulcerated, usually on the volar surface of the fingers or palms. It occurs most frequently on the distal upper extremity, but it may also occur on the lower extremities and occasionally in the trunk or head and neck region. Epithelioid sarcoma has a tendency to spread locally through lymphatic channels or along fascial planes, and may give rise to multiple local nodules. The clinical differential diagnosis includes mycobacterial or deep fungal infection, squamous cell carcinoma, and other soft tissue sarcomas. The male-to-female ratio is approximately 2:1, and it affects mainly young adults.
4. How is the diagnosis of epithelioid sarcoma made?
The diagnosis of epithelioid sarcoma is made by typical histologic features. The tumor is composed of malignant, eosinophilic, epithelioid and spindle cells arranged in nodules that often demonstrate central necrosis. Immunohistochemistry, special stains, and tissue culture are used to assist the diagnosis. The tumor cells demonstrate staining with both mesenchymal markers (vimentin), as well as epithelial markers (keratins and epithelial membrane antigen).
5. How are epithelioid sarcomas treated?
Early radical local excisional surgery is required. The local recurrence rate has been reported to range from 35% to 77%. Multifocal recurrences are common because the tumor spreads insidiously along tendons, fascial planes, nerves, and blood vessels. Adjuvant radiotherapy is often used to lower the risk of local recurrence; however, amputation is sometimes required. Chemotherapy with ifosfamide and doxorubicin is recommended for metastatic disease.
7. What are the prognostic factors of epithelioid sarcoma?
10. How does angiosarcoma of the scalp and face in the elderly present?
It presents as an erythematous or hemorrhagic bruiselike patch on the central face or scalp, which spreads centrifugally and evolves into nodules that bleed easily and ulcerate (Fig. 47-1). There is often extensive infiltration, and the extent of the tumor is often underestimated clinically.
11. What are the clinical course and prognosis for angiosarcoma?
In the largest reported series of 72 patients, only 12% survived for 5 years. Metastases to the cervical nodes and hematogenous metastases to the lungs, liver, and spleen occur. Because of their rarity, there are no clear definitive or significant prognostic factors identified for angiosarcoma, but histologic grade, tumor diameter, depth of invasion, positive margins, metastases, and tumor recurrence are potential predictors of outcome.
12. Is there an effective treatment for angiosarcoma?
Early diagnosis and complete surgical excision offer the best chance of survival. However, because the lesions tend to be multicentric, extensive, and rapidly growing over the face and scalp, surgical excision is rarely successful. A combined-modality approach is often used, including excision of disease with negative margins if possible, with adjuvant radiotherapy. Chemotherapy is usually recommended in cases of systemic disease.
13. What is the clinical presentation of angiosarcoma arising in chronic lymphedema?
This rare tumor, also called Stewart-Treves syndrome, arises as cutaneous and subcutaneous firm, coalescing, violaceous nodules on a background of nonpitting edema, often in the inner aspect of the upper arm. It occurs on average 10 years following mastectomy and lymphadenectomy (range 1 to 30 years). It is less commonly associated with filarial, congenital, traumatic, or idiopathic lymphedema.
15. What are the histologic features of angiosarcomas?
Angiosarcomas are composed of an anastomosing network of well-formed, irregular vascular channels, often lined by flattened endothelial cells. They exhibit a highly infiltrative pattern, dissecting and splitting collagen bundles. Poorly differentiated angiosarcomas may closely resemble carcinomas or other soft tissue sarcomas, with only subtle vascular lumen formation.
16. What is Merkel cell carcinoma (MCC)?
Merkel cell carcinoma (MCC), also known as primary neuroendocrine carcinoma of the skin, is an aggressive malignant neoplasm. The tumor was initially thought to arise from Merkel cells, receptors of mechanical stimuli with a high density on hairless skin. However, the tumor is now thought to arise from a less–well-differentiated progenitor cell of probably epithelial origin.
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