A 79-year-old woman with a 2-decade history of “treated” chronic lymphocytic leukemia presented with an 8-mm erythematous plaque with telangiectasia on the right breast. Histopathologic examination of shave biopsy showed nodular lymphoid aggregates containing atypical secondary lymphoid follicles surrounded by small mature lymphoid cells with round nuclear contours at the periphery in the superficial dermis (panels A-B; hematoxylin and eosin stain, original magnification ×40 [A] and ×100 [B]). Although CD20 and CD10 highlight secondary germinal center (GC) B cells (panels C-D, respectively; original magnification ×200 [C] and ×40 [D]), the small cells from the perifollicular region are partially and dimly positive for CD20 (panel C) but negative for CD10 (panel D). In comparison with CD3 (panel E; original magnification ×40), the perifollicular lymphocytes are strongly positive for B-cell lymphoma 2 (BCL2) (panel F; original magnification ×40), but the GC B cells are dimly and partially positive for BCL2 (panel F). Interestingly, the perifollicular cells are positive for CD5 (panel G; original magnification ×100) and lymphoid enhancer binding factor 1 (LEF1) (panel H; original magnification ×100). Polymerase chain reaction showed monoclonal rearrangements of both immunoglobulin H (IgH) and IgK with 2 peaks in IgH framework 1, 2, IgK, and the κ-deleting element (KDE) (data not shown). The overall findings support composite small lymphocytic lymphoma (SLL) and primary cutaneous follicle center lymphoma (PCFCL).

Composite lymphoma (CL) is a very rare type of lymphoma. To our best knowledge, this is the second published case of cutaneous composite SLL and PCFCL, but the first CL in which the SLL component occupies the perifollicular region exhibiting a mantle zone–like growth pattern.