Mycosis fungoides (MF) is the most common primary cutaneous T-cell lymphoma. Although it was first described in 1833, our understanding of this disease has continued to evolve. From a diagnostic perspective, the diagnosis of MF can be challenging particularly in the early stages of the disease, because of overlap between the histological features of early MF lesions and many other inflammatory dermatoses. Furthermore, there has been an emergence of numerous clinicopathologic and immunohistochemical variants of MF reported in the literature. Although the prognostic significance of some of the rare variants is still not fully understood, certain variants, such as folliculotropic and bullous MF, have demonstrated less indolent clinical courses compared with classic MF and necessitate aggressive therapeutic measures. Thus, it is important for dermatologists and dermatopathologists to be knowledgeable of the widely varied clinical, histological, and immunohistochemical presentations of MF to arrive at a prompt and accurate diagnosis and initiate appropriate treatment.

BackgroundMalignant gastrointestinal neuroectodermal tumor (GNET) is an extremely rare entity that was first described by Zambrano et al. in 2003 as “Clear cell sarcoma-like tumor of the gastrointestinal tract”. It shares some of the histological features of clear cell sarcoma (CCS) but lacks the immunohistochemical reactivity for melanocytic markers. We report a case of GNET that was initially misdiagnosed as gastrointestinal stromal tumor (GIST). Recognizing this entity is important to avoid misdiagnosis.Case presentationA case of an 18-year-old male presented with a small intestinal tumor. Histologically it was characterized by polygonal cells arranged in pseudoalveolar pattern and situated in the muscularis propria. Scattered osteoclast-like multinucleated giant cells were also noted. The neoplastic cells were positive for S-100 protein and negative for HMB-45, Melan A, smooth muscle actin, desmin and CD117. EWSR1 gene rearrangement was detected by fluorescence in situ hybridization (FISH) analysis. The patient returned with recurrence after 36 months’ management by surgical resection and died one year later.ConclusionsGNET can be mistaken histologically for other non-epithelial gastrointestinal tumors. Awareness of its existence and diagnostic criteria by the pathologist is necessary to avoid misdiagnosis, particularly as GIST, CCS or malignant peripheral nerve sheath tumor (MPNST).

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Primary pulmonary Hodgkin lymphoma (PPHL) is a rare disease. Herein, we report a case of PPHL with diagnostic concerns encountered during initial evaluation which is of paramount importance to keep the differential diagnosis in cases with high index of suspicion for this rare entity.