Primary cutaneous follicle center lymphoma (PCFCL) with a diffuse growth pattern

PCFCL with a diffuse growth pattern in a 62-year-old woman with a 5 mm pearly scalp papule of 3 months' duration.
(A) A large mass of lymphocytes extends diffusely from the upper reticular dermis to the subcutaneous tissue.
(B) The lymphocytes are predominantly large centrocytes with some centroblasts. Some of the cells appear spindled.
(C) They express BCL6 and lack CD10 (not shown).
(D) Immunostaining for CD21 revealed very focal small remnants of follicular dendritic cell meshworks.