Deeply eosinophilic cell variant of signet-ring type of gastric carcinoma: a diagnostic dilemma.

Signet-ring cell type of gastric carcinoma can easily escape detection by the pathologist, and this confusion is compounded by the presence of morphologic patterns other than the conventional appearance. One such morphologic variant is composed of deeply eosinophilic cells containing minute cytoplasmic granules with neutral mucin. With this morphology, epithelioid gastrointestinal stromal tumor (GIST), and hepatoid and rhabdoid variants of adenocarcinoma enter the list of diagnostic possibilities, and accurate diagnosis is essential for therapeutic and prognostic considerations. We report a 28-year-old man who presented with dyspepsia, nausea, vomiting, and black-colored stools. Endoscopy revealed a growth at the incisura, a biopsy specimen from which was reported as a poorly differentiated tumor. The patient underwent subtotal gastrectomy and the resected specimen showed a 6.5 x 4-cm circumferential growth in the antropyloric region. Histological sections from the growth showed transmural infiltration by deeply eosinophilic cells with hyperchromatic nuclei. A differential diagnosis of epithelioid GIST, rhabdoid variant, hepatoid variant, and signet-ring cell adenocarcinoma was considered. Special stains and immunohistochemistry confirmed the tumor to be a variant of signet-ring cell adenocarcinoma of the stomach. Morphologic variations of signet-ring cell carcinoma pose an important diagnostic dilemma, which has therapeutic and prognostic significance for the patient. These variants need to be recognized by pathologists to enable an accurate diagnosis.