Cutaneous Malignant Melanoma With Rhabdoid Morphology and Smooth Muscle Differentiation: A Challenging Histopathologic Diagnosis.

Divergent differentiation or metaplastic change is a rare feature exhibited occasionally in malignant melanoma (MM), which is characterized by the development of morphologically, immunochemically, and/or ultrastructurally nonmelanocytic cells within the tumor. Smooth muscle differentiation in MM is an exceedingly rare phenomenon reported only in a few cases in the literature. We report the case of a 69-year-old woman who presented with a pure dermal amelanotic MM with smooth muscle cell differentiation and an area of rhabdoid morphology, which made the accurate histopathologic diagnostic of MM challenging.

Ileal Intussusception in an Adult Caused by a Locally Invasive Inflammatory Fibroid Polyp: A Case Report.

Inflammatory fibroid polyps (IFPs) are rare mesenchymal neoplasms affecting the gastrointestinal tract which are considered benign and noninvasive. We present a case of an invasive IFP in a 46-year-old woman who presented with signs of intestinal obstruction due to ileal intussusception. A segment of the small intestine was resected and subsequently intestinal continuity was restored. A polypoid lesion was found obstructing the lumen. Histopathology revealed a mesenchymal proliferation of spindle and stellate cells, without cytological atypia, arranged in a fibromyxoid stroma. The tumor cells were located in the submucosa but also infiltrated the muscularis propria and the subserosa and were CD34 positive. The molecular study by PCR showed mutation in exon 12 of the PDGFRA gene. IFP is considered a true neoplasm and can also be considered as a potentially invasive lesion.

Ileal Intussusception in an Adult Caused by a Locally Invasive Inflammatory Fibroid Polyp: A Case Report / Invaginación ileal en un adulto secundaria a un pólipo fibroide inflamatorio localmente invasivo: Reporte de un caso

Inflammatory fibroid polyps (IFPs) are rare mesenchymal neoplasms affecting the gastrointestinal tract which are considered benign and noninvasive. We present a case of an invasive IFP in a 46-year-old woman who presented with signs of intestinal obstruction due to ileal intussusception. A segment of the small intestine was resected and subsequently intestinal continuity was restored. A polypoid lesion was found obstructing the lumen. Histopathology revealed a mesenchymal proliferation of spindle and stellate cells, without cytological atypia, arranged in a fibromyxoid stroma. The tumor cells were located in the submucosa but also infiltrated the muscularis propria and the subserosa and were CD34 positive. The molecular study by PCR showed mutation in exon 12 of the PDGFRA gene. IFP is considered a true neoplasm and can also be considered as a potentially invasive lesion

Los pólipos fibroides inflamatorios (PFIs) son considerados como neoplasias mesenquimales inusuales que afectan al tracto gastrointestinal. Son consideradas benignas y generalmente no invasivas. Presentamos un caso de PFI invasivo en una mujer de 46 años que evidenció signos de obstrucción intestinal por invaginación ileal. Se realizó resección de un segmento de intestino delgado y posterior desinvaginación manual del segmento resecado, observándose una lesión polipoide que obstruía la luz. Histológicamente, la lesión estaba constituida por una proliferación mesenquimal de células fusiformes y estrelladas sin atipia citológica, dispuestas en un estroma fibromixoide. Se encontraba localizada en la submucosa, aunque también infiltraba la capa muscular propia y la subserosa. Las células de la lesión fueron positivas para CD34. El estudio molecular mediante PCR demostró mutación en el exón 12 del gen PDGFRA. Actualmente el PFI es considerada una verdadera neoplasia que excepcionalmente tiene carácter invasivo

Proliferación linfoide atípica intravascular de linfocitos T-CD30+ sobre granuloma piogénico (hemangioma capilar lobular) / Intravascular atypical T-cell proliferation T-CD30+ in a pyogenic granuloma (lobular capillary hemangioma)

En este trabajo presentamos el caso de una proliferación linfoide atípica constituida por una población de linfocitos T-CD30+, que ocupa los vasos de un granuloma piogénico (hemangioma capilar lobular). Esta población linfoide T (CD4) presenta atipia y alto índice proliferativo, por lo que resulta necesario descartar un linfoma intravascular. Se ha descrito recientemente una proliferación de estas características que puede ser malinterpretada como un linfoma intravascular debido a la atipia y al alto índice mitótico. Los pacientes tienen buen pronóstico y no presentan signos de linfoma. El reordenamiento T resultó nulo, y la paciente continúa asintomática hasta el presente. Nuestro objetivo es presentar esta nueva entidad de carácter reactivo que simula un linfoma, y resaltar la importancia de su reconocimiento en el diagnóstico diferencial de un linfoma intravascular cutáneo (AU)

We report a case of atypical intravascular CD30+ T-cell proliferation in a patient with pyogenic granuloma (Lobular Capillary Hemangioma). The T (CD4) cell population showed cell atypia and a high proliferation index, thus it was necessary to discard an intravascular lymphoma. Cutaneous intravascular lymphoma commonly represents a diffuse large B-cell lymphoma with predominantly intravascular growth, although it could be also represented by intravascular T cell lymphomas. Recently a CD30+ T-cell proliferation was described that could mimic an intravascular T cell lymphoma. In our case TCR rearrangement was null and the patient remained healthy. We report a new case of this benign reactive process and discuss the importance of its differential diagnosis (AU)