FINAL DIAGNOSIS   B-cell lymphoid neoplasm with high-grade features (abdominal lymphomatosis)

DISCUSSION

Diffuse seeding of the peritoneum with carcinomas, such as ovarian, gastric or colonic carcinoma, is a well recognized phenomenon. However, extensive involvement of the abdominal cavity by lymphoma (abdominal lymphomatosis) is rare and primary presentation with symptoms related to peritoneal disease is even rarer.

Abdominal lymphomatosis is a rare presentation of lymphoma with fewer than 30 cases reported (1, 2). Most of the patients presents with abdominal pain and discomfort, weight loss, fatigue and night sweating. Mean age of presentation is 60-70. Radiographically, peritoneal thickening with contrast enhancement is the most common finding. This is often accompanied by ascites (75%), bowel wall thickening (67%), liver and spleen enlargement (68%), and retroperitoneal lymphadenopathy (63%) (1). In the absence of a clinical history of lymphoma, radiologically, abdominal lymphomatosis is frequently misdiagnosed radiologically as abdominal carcinomatosis, as in the present case. In one case report, association of peritoneal lymphoma with a raised CA125, a tumor marker which is commonly raised in ovarial carcinoma was also reported, making presurgical, radiological and clinical diagnosis more difficult (3). The most common subtype of abdominal lymphomatosis is diffuse large B-cell lymphoma (67%), followed by small cell lymphma/chronic lymphocytic leukemia (13%) (1). The subtyping of the current case was difficult due to the lack of TdT staining and failed Ki-67 staining. However, given the sheets of proliferation of small to intermediate sized blastoid cells, Burkitt lymphoma, rare TdT-negative B-lymphoblastic lymphoma/leukemia, or blastoid follicular lymphoma may be considered for differential diagnosis.

This case illustrates how abdominal lymphomatosis diffusely involving peritoneum, omentum, and pelvic organs can present with a clinical picture perfectly mimicking carcinomatosis; only histological examination and immunohistochemical workup can make the differentiation. Accurate diagnosis is important because the treatment for lymphoma is radically different from the treatment of carcinoma.