We present a case of granular cell atypical fibroxanthoma of the scalp. The neoplasm occurred as a tender nodule on the frontal scalp of an 82-year-old Caucasian man. Histology demonstrated a diffuse proliferation of atypical epithelioid cells with abundant granular cytoplasm. Many of the cells had large irregular nuclei and atypical mitotic figures were present. Immunohistochemical stains were positive for CD68 and procollagen 1 and negative for cytokeratin, HMB-45 and S-100 protein. The granular cell phenotype has been observed in other cutaneous neoplasms including granular cell tumors, dermatofibromas, dermatofibrosarcoma protuberans, fibrous papules, basal cell carcinomas, leiomyosarcomas, angiosarcomas and primitive polypoid granular cell tumors. We discuss the differential diagnosis and review the previously reported cases of this rare variant of atypical fibroxanthoma.
Cutaneous malignant peripheral nerve sheath tumors (MPNSTs) are rare entities compared with their deep soft tissue counterparts. We describe two cases of cutaneous MPNSTs. The first case, occurring in a 27-year-old woman with neurofibromatosis I, presented with recent growth of a pre-existing nodule on her back. A biopsy showed a densely cellular area within a conventional neurofibroma composed of atypical, hyperchromatic epithelioid and spindled cells with frequent mitotic figures (MFs). The second case presented in an 88-year-old man with no stigmata of neurofibromatosis as a rapidly growing subcutaneous tumor of the right calf. A biopsy showed a diffuse neurofibroma that abruptly transitioned to a densely cellular proliferation of hyperchromatic atypical spindled cells arranged in short fascicles with frequent MFs. The diagnosis of MPNST was rendered in both cases. MPNSTs of the dermis and subcutis are rare sarcomas. They can occur as sporadic tumors or in the setting of neurofibromatosis. They are often associated with pre-existing neurofibromas. Increase in size of pre-existing neurofibromas is an indication for biopsy. Recognition of the cellular atypia, increased cellularity and mitotic activity is key to the diagnosis.
Myeloid leukemia cutis (LC) is the cutaneous involvement by neoplastic leukocytes of the myeloid series. Myeloid LC may occur de novo or concurrently with acute myeloid leukemias, chronic myeloid leukemias, other myeloproliferative disorders or myelodysplastic syndromes. We describe an unusual case of cytophagic S-100 protein immunoreactive leukemia cutis presenting in an 87-year-old woman without prior history of myeloid leukemia or other hematologic disorders. We outline key histologic and immunohistochemical features that aide in the diagnosis of LC. The presence of cytophagocytosis on histologic examination, a phenomenon more commonly associated with lymphoid rather than myeloid malignancies, provided a clue to the possibility of a malignant process. The atypical myeloid infiltrate showed S-100 protein positivity, an unusual finding that may be seen in LC. Although not commonly reported in LC, the presence of S-100 protein positivity and cytophagocytosis should not lead to the premature exclusion of LC as a possible diagnosis until a thorough clinical, histologic and immunohistochemical evaluation is performed. In addition, the presence of cytophagocytosis has been shown to have prognostic significance for patients with myeloid leukemia.
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