A rare occurrence of a steroid cell tumor of the pelvic mesentery: a case report.

IntroductionSteroid cell tumors are microscopically characterized by abundant eosinophilic or vacuolated cytoplasm that is often positive for fat stains. These tumors could be of ovarian or ectopic adrenal origin. We present a rare case of a steroid cell tumor arising from the pelvic mesentery.Case presentationA 31-year-old Asian woman was undergoing treatment for infertility and virilizing symptoms. She underwent laparoscopy followed by laprotomy for a suspected ovarian cyst/pelvic mass. During the laprotomy, a mass of 9 × 7 cm was detected in the pelvic mesentery.Microscopically, the tumor showed large cells arranged predominantly in sheets with abundant granular cytoplasm and large vesicular nuclei with prominent nucleoli. The tumor was seen infiltrating surrounding adipose tissue. Immunohistochemically, the tumor cells showed strong positivity for kertain, inhibin, vimentine, melan-A, neuron-specific enolase, chromogranin, and S-100 protein and focal positivity to epithelial membrane antigen. An MIB1 index showed 4% nuclear positivity. The tumor cells were negative for calretinin, desmin, and muscle actin. Considering the clinical findings, histomorphology, and immunohistochemistry, we made the diagnosis of extraovarian and extra-adrenal steroid cell tumor (not otherwise specified) of the pelvic mesentery.ConclusionsWe report an extremely rare case of an extraovarian and extra-adrenal steroid cell tumor of the pelvic mesentery. The tumor was a cause of virilizing symptoms and infertility in the patient. Surgical removal of the tumor reverted the symptoms of virilization, and the patient subsequently conceived. Steroid cell tumors should be considered in differential diagnosis among women presenting with infertility and symptoms of virilization.