Incidence of primary extranodal lymphoma involving gastrointestinal tract by histological type at Ilorin.

We report 21 cases of primary extranodal lymphoma of the gastrointestinal tract over a period of 10 years (1986-1995) at the Department of Morbid Anatomy and Histopathology, University of Ilorin Teaching Hospital, Ilorin, Kwara State of Nigeria. This represents 6% of the total gastrointestinal tract malignancies diagnosed during same period. All were Non Hodgkin's Lymphoma. The ages ranged from 4 to 60 years, while the mean age was 23 years. Male to female ratio was 4:3. The anatomic sites involved were stomach 4, (19%), small intestine 13, (62%), and large intestine 4, (19%). There was no single case of rectal lymphoma. The histological types were Burkitt's lymphoma 9 (42.8%), diffuse mixed (small and large) cells 4 (19.1%), diffuse large cells 4 (9.1%), small lymphocytic cells, 2 (9.5%) and large immunoblastic cells 2 (9.5%). All the cases of Burkitt's lymphoma occurred under 20 years of age. Distribution into prognostic groups (grades) according to working formulation for clinical usage was low grade, 2 (9.5%), intermediate grade, 8 (38.1%) and High grade, 22 (52.4%). We conclude that extranodal malignant lymphoma involving the gastrointestinal tract is not rare and should be considered for differential diagnosis in gastrointestinal tract malignancies.