High-grade non-Hodgkin's lymphoma of ovary presenting as peritonitis.

Primary ovarian lymphoma is rare, with ovary more commonly involved secondarily in generalized disease. Primary ovarian lymphoma presents as mass in the ovary with chronic symptoms; an acute presentation has not been described previously. A 75-year-old female presented with acute abdomen and features of peritonism. Computed tomography and magnetic resonance imaging demonstrated large mass in left ovary along with infiltration of adjacent sigmoid colon causing perforation and pneumoperitoneum. Few jejunal loops were also involved. Intraoperatively, there was left ovarian mass infiltrating the sigmoid colon with perforation and fecal peritonitis. Distal jejunal loops were adherent to the tumor. The involved sigmoid colon was resected with total abdominal hysterectomy, bilateral salpingo-oophorectomy and resection of adherent jejunal loops. Histopathology revealed ovarian tissue with necrotic neoplasm composed of small-to medium-sized round cells exhibiting nuclear irregularity and scanty cytoplasm, forming discohesive sheets with the neoplasm infiltrating the retroperitoneal remnant tissue and resected bowel. This case highlights an unusual presentation of primary ovarian lymphoma.