Langerhans cell sarcoma: an unusual microscopic presentation.

A 70-year-old Caucasian male presented to our clinic for a pruritic eruption progressing over several months. He complained of fatigue with a 20-pound weight loss over the past year. On presentation, the patient had browny-yellow to violaceous, purpuric, macular and papular lesions on the legs, arms, lower abdomen and back. Initial biopsy showed an angiocentric infiltrate with a suggestion of intraluminal proliferation; CD31 and Fli-1 positivity suggested either reactive angioendotheliomatosis or an unusual intravascular histiocytosis. Further excisional biopsies demonstrated perivascular collections of cells with ample cytoplasm, prominent nuclear pleomorphism and mitotic activity. The nuclei demonstrated nuclear folding, grooves and indentations. The atypical cells were S100, CD1a and CD56 positive with immunohistochemistry. A diagnosis of Langerhans cell sarcoma (LCS) was made. LCS is a rare, aggressive malignancy that can involve multiple organs including the skin, lymph nodes, lung, bone marrow, spleen, heart, and brain. The skin and lymph nodes are commonly involved, and the cutaneous presentation varies greatly. Immunohistochemistry characteristically shows CD1a and S100 positivity. CD56 expression is uncommon and often portends a poor prognosis. There is no established treatment of LCS due to its rarity. Surgery, radiation, and chemotherapy have been used with varied outcomes. Our patient was treated with prednisone with improvement of cutaneous disease. He did not develop systemic involvement, but died 1.5 years later from complications associated with heart failure. Langerhans cell sarcoma should be considered when faced with an unusual angiocentric infiltrate in which initial immunohistochemical staining results may be misleading.