We report the second case of cutaneous myelofibrosis with a documented JAK2 activating mutation involving the scalp of a 67-year-old woman with primary myelofibrosis in her marrow. In contrast to the previous case, the biopsy revealed extensive lesional collagen deposition and closely mimicked a fibrohistiocytic proliferation. Similar rare lesions occurring in the setting of myeloproliferative neoplasms have been called sclerosing extramedullary hematopoietic tumors. These entities appear histomorphologically and etiologically distinct from extramedullary hematopoiesis, and their diagnosis should prompt the workup for a myeloproliferative neoplasm in the absence of an antecedent diagnosis. The presence of the JAK2 mutation in our case confirmed that the lesions represented skin involvement by a neoplastic myeloid proliferation and not compensatory extramedullary hematopoiesis. Our patient died of disease several months following the appearance of her lesions, which is in keeping with other reports that suggest that cutaneous myelofibrosis may serve as an independent poor prognostic sign in otherwise advanced primary myelofibrosis. A review of the literature further emphasizes the importance of distinguishing this entity from mesenchymal neoplasms and acute myeloid leukemia involving the skin.

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is an uncommon non-Hodgkins primary cutaneous lymphoma that typically presents as subcutaneous nodules on the extremities or trunk. Here, we report an unusual case of systemic panniculitic T-cell lymphoma with predominantly mesenteric extra-cutaneous involvement and an aggressive clinical course with histopathologic and immunophenotypic features that mimic SPTCL. This case serves to expand the body of literature regarding systemic SPTCL-like disorders with prominent extra-cutaneous involvement.

Knowledge of these cutaneous manifestations provides an insight into the state of colonic health. These clues alert the clinician to the potential for life-threatening consequences, which leads to vigilant screening and hopefully earlier diagnosis.

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