12/09/2004 Case 4: Anaplastic large cell carcinoma

Clinical History:

A 61 year old woman presented with signs and synlplrnns of increased intracranial pressure and was found to have a right fron toparietal tumor. She had a history of prior (non-CNS) lymphoma but more details were not known.

Diagnostic Notes:

The excision surgical specimen showed a very poorly differentiated tumor with discohesive cells, many of which were quite large and markedly pleiomorphic. The differential diagnosis included Anaplastic Large Cell Carcinoma, Giant Cell Glioblastoma, and Melanoma; it was not thought by appearance to be very suggestive of lymphoma. Immunostains showed no immunopositivity for GFAP, S]OO, HMB45, CD30, TTF 1, Chromogranin, ER/PR, or Breast Gross Cystic Fluid Antigen. However there was immunopositivity for low molecular weight keratin (CAM5.2), for a pan-keratin cocktail (AE1/AE3), Vimentin, and CK7; CK20 was negative. A variety of other markers was also negative. The diagnosis, then, was one of Anaplastic Large Cell Carcinoma.

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