#00065424

A 64-year-old male with a history of CD10 positive B-cell lymphoproliferative disease. Imaging studies revealed an 18 x 17 x 10 cm enhancing mass in the right upper quadrant of the abdomen. PET/CT scan revealed fluorodeoxyglucose (FDG) avid multicompartmental lymphadenopathy above and below the diaphragm. The complete blood counts were within the normal limit. Lactate dehydrogenase level was elevated (249 U/L, normal range: 135-225 U/L).

Histologic sections of the needle core biopsy from the mass showed a neoplastic proliferation in a vague nodular growth pattern.  (panel A; original magnification, 10x). The polarization, tingible body macrophages, and mantle zones were not identified. The nodules are composed of small to intermediate size with cleaved nuclei. Many cells showed eccentrically placed nuclei and vacuolated cytoplasm, with signet ring like morphology (panels B-C; original magnification, 400x).

By immunohistochemistry, the lymphoma cells were positive for BCL6 (panel D), CD20 (panel E), BCL2 (panel F), and CD10 (panel G). CD21 highlighted the follicular dendritic cell meshworks (panel H). Ki-67 showed a low proliferation index of < 10% (panel I). Flow cytometry immunophenotyping detected kappa light chain restricted monoclonal B-cells (80% of total cells), positive for CD10 and negative for CD5 or CD11c. 

The diagnosis of follicular lymphoma with signet ring-like cells was rendered. Clinically, these lymphomas do not differ in behavior from the more typical follicular lymphoma, and prognosis depends more on the grade.