A 45-year-old male presented to his primary care physician with epiphora. Examination identified bilateral conjunctival masses comprising CD20+ B lymphocytes expressing CD5, BCL2, and cyclin D1. A diagnosis of mantle cell lymphoma was rendered. Staging positron emission tomography scans revealed numerous extraocular sites of involvement. Bone marrow biopsy was normocellular with unremarkable flow cytometric immunophenotyping; however, a single lymphoid aggregate was noticed (panel A). Although it appeared to be benign, immunostaining for CD3, CD20, and cyclin D1 was performed, displaying retained immunoarchitecture for CD20 (panel B) and CD3 (panel C). Cyclin D1 highlighted a small subset of B cells within the mantle zone (panel D), indicating low-level involvement by lymphoma. This peculiar pattern of cyclin D1 positivity, in which cyclin D1–positive cells encircled follicles, is characteristic of an early or in situ mantle cell lymphoma.
In situ mantle cell lymphoma is rare and exhibits cyclin D1 positivity within the innermost mantle zone B lymphocytes, often partially encircling follicles. In contrast, full encircling of follicles by cyclin D1–positive cells has been proposed to indicate early involvement by mantle cell lymphoma. To the best of our knowledge, this pattern has not been reported in the marrow. This morphologic observation in a patient with overt mantle cell lymphoma likely represents early homing of the primary lymphoma to the marrow.
A 45-year-old male presented to his primary care physician with epiphora. Examination identified bilateral conjunctival masses comprising CD20+ B lymphocytes expressing CD5, BCL2, and cyclin D1. A diagnosis of mantle cell lymphoma was rendered. Staging positron emission tomography scans revealed numerous extraocular sites of involvement. Bone marrow biopsy was normocellular with unremarkable flow cytometric immunophenotyping; however, a single lymphoid aggregate was noticed (panel A). Although it appeared to be benign, immunostaining for CD3, CD20, and cyclin D1 was performed, displaying retained immunoarchitecture for CD20 (panel B) and CD3 (panel C). Cyclin D1 highlighted a small subset of B cells within the mantle zone (panel D), indicating low-level involvement by lymphoma. This peculiar pattern of cyclin D1 positivity, in which cyclin D1–positive cells encircled follicles, is characteristic of an early or in situ mantle cell lymphoma.
In situ mantle cell lymphoma is rare and exhibits cyclin D1 positivity within the innermost mantle zone B lymphocytes, often partially encircling follicles. In contrast, full encircling of follicles by cyclin D1–positive cells has been proposed to indicate early involvement by mantle cell lymphoma. To the best of our knowledge, this pattern has not been reported in the marrow. This morphologic observation in a patient with overt mantle cell lymphoma likely represents early homing of the primary lymphoma to the marrow.
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