ThinPrep Cytological Findings of Desmoplastic Small Round Cell Tumor with Extensive Glandular Differentiation: A Case Study
A 31-year-old man was admitted for constipation and abdominal pain that had persisted for a month. The patient was transferred for an abdominal mass on an abdominal sonogram at local clinic. Physical examination revealed a fist-sized mass on the right lower quadrant of abdomen. The initial abdominopelvic computer-tomography images showed a 5.5 cm-sized mass at the right lower quadrant with surrounding seeding nodules and mesenteric lymphadenopathy, suggesting carcinomatosis (). The colonoscopy revealed a diffuse luminal narrowing due to the extrinsic masses (). The laparoscopic finding showed multiple disseminated, variable-sized, firm, whitish masses or plaques on the hepatic capsule and the serosal surface of the colon ().\nThe initial peritoneal-washing fluid (ThinPrep) diagnosed the tumors as "adenocarcinoma" because the clusters of tumor cells revealed finger-like buddings (). The high power field disclosed common outer-cell borders, intracytoplasmic vacuoles, convoluted nuclei, and relatively large prominent nucleoli. However, retrospective cytological review of the distinct nuclear moldings that were also identified, favored the diagnosis of small round cell tumors (). There were a few fragments of fibrillary stroma (). The immunocytochemical stainings were positive for vimentin (), pancytokeratin (panCK) (), and vaguely positive for desmin ().\nAfter eight months, a malignant pleural-effusion was detected. Conventional fluid cytology showed cytological features similar to those seen from the peritoneal washing, but angulated nuclei with distinct nuclear moldings were also present (). In ThinPrep findings, the clusters were more rounded, with three-dimensional structures, and even extracellular mucin content, very similar to adenocarcinoma ().\nThe initial laparoscopic biopsy showed typical findings of DSRCT, desmoplastic stroma, and variable-sized nests of small round cells (). Four months later, a second biopsy specimen was obtained during T-loop colostomy for a marked-intestinal-obstruction relief. There were multiple nodules on the mesentery. Each nodule had diverse morphology (). The mucicarmine staining was positive for intraglandular content (). Immunohistochemical staining disclosed dot-like desmin positivity (). Co-expression of panCK and vimentin was variable in each nodule. In the gland-forming portion, the tumor cells were strongly positive for panCK () and weakly positive for vimentin. Neuronal differentiation was also variable ().\nDespite the diagnosis of DSRCT, the patient refused chemotherapy and the disease rapidly progressed. The patient passed away a year after the first biopsy due to the increase in size and volume of the intra-abdominal masses and associated complications (intestinal and ureteral obstruction, hydronephrosis, and chronic renal failure).