Abstract
A 43-year-old gentleman presented with painful, multifocal ulcerations on his bilateral thighs. Biopsy demonstrated a dense dermal infiltrate that invaded into the subcutaneous tissue. The infiltrative cells stained positive for CD207, CD1a and S100. The infiltrate had frequent atypia and mitoses. As such, the patient was diagnosed with Langerhans cell sarcoma. Langerhans cell sarcoma is a rare neoplastic disorder. According to the Histiocyte Society, there are 5 groups in classifying histiocytoses and neoplasms of the dendritic cell lineages. Langerhans cell sarcoma falls under the malignant group and is distinct from Langerhans cell histiocytosis. However, these sarcomas will stain positive for typical Langerhans cell markers. Langerhans cell sarcoma has been diagnosed less than 100 times in the literature. It can present with both cutaneous and systemic findings. There does not appear to be an age predilection with an age range of 11 months to 81 years. In a systematic review, 75% of patients had lymph node involvement, 50% had cutaneous involvement and many had lung, liver, or spleen involvement. The cutaneous manifestation varies from indolent appearing nodules to ulcerations or even fungating tumors. The pathogenesis is poorly understood but is thought to be driven by mutations in the RAS/MAPK/BRAF pathway. Diagnostic criteria include malignant cytological features as well as expression of typical Langerhans cell markers. Treatment options include surgical excision, radiation, chemotherapy, or bone marrow transplantation. More targeted therapies have shown promise in case reports. The prognosis is poor in metastatic disease but can be favorable if disease is localized.