A Large Lumbar Adnexal Neoplasm Presenting Characteristics of Eccrine Poroma and Poroid Hidradenoma.

Poroma is a rare benign neoplasm that derives from eccrine sweat glands epithelium. Its histological subtypes, with respect to its position within skin layers, are eccrine poroma, hidroacanthoma simplex, poroid hidradenoma, and dermal duct tumor. Poromas commonly exhibit benign clinical behavior as they are usually small and asymptomatic and do not exhibit malignant behavior. Although their histological subtypes share similar histological characteristics, they rarely coexist in the same tumor. In this report we present the case of an unusual poroma in terms of histological and clinical behavior as it was large and presented histological characteristic of both eccrine poroma and poroid hidradenoma. Coexistence of different histologic subtypes in the same tumor indicates simultaneous tumorigenesis, differentiation from one cell type to another, or parallel differentiation from a common progenitor cell. Implications in treatment remain unknown partly due to the rarity of such cases.

GIST mimicking an hyperplastic polyp of descending colon.

INTRODUCTION: The authors describe a case of a patient who underwent resection of a colonic GIST mimicking a hyperplastic polyp of the descending colon. CASE REPORT: We report the case of a colonic Gastrointestinal Stromal Tumor (GIST) of a 55 years old male patient who was admitted to us because of rectal bleeding and altered bowel habits. Patient was initially diagnosed for hyperplastic polyps of the descending colon and thus surgical treatment was proposed. Post operative histological examination of the polypsi revealed a GIST that was classified as one of a very low malignancy based on NIH consensus risk stratification system. Patient is followed-up and until today presents no sign of disease. DISCUSSION: Gastrointestinal stromal tumor (GIST) is a rare mesenchymal tumor commonly occurring in the gastrointestinal track. It is usually found at the stomach and small bowel while colonic, rectal and esophageal GIST are rare. Diagnosis of GIST is based more on histological examination and less on clinical findings or radiological image since they are nonspecific. Complete surgical resection with negative margins remains the only effective treatment against GIST yet imatinib mesylate, a tyrosine kinase growth factor receptor inhibitor, is found to be effective against GIST and is currently used as treatment for metastatic, recurrent or non-operable GIST Although the diagnosis is difficult, especially in the less common sites, the Authors suggest that GIST should be included in the differential diagnosis of colonic masses.