Also known as: cutaneous B-cell lymphoid hyperplasia, lymphadenosis benigna cutis, lymphocytoma cutis, pseudolymphoma of Spiegler-Fendt

Clinical Features:

• Reactive proliferation of B-cells
• May be secondary to a variety of immune provocations, such as insect bites, drugs, vaccinations, tattoos and infection with Borrelia burgdorferi.
• Common sites are the face, nipple and scrotum.
• Presents as a solitary, smooth, red to brown nodule.

Histologic Features:

• Well-circumscribed nodular collections of predominantly small mature lymphocytes within the dermis and sometimes subcutis
• The nodules are frequently more densely packed within the upper dermis than the lower dermis ("top heavy").
• Germinal centers are frequently present.
• Important in the differential diagnosis with lymphoma is the admixture of smaller numbers of other cell types within the lymphoid collections: eosinophils, plasma cells and histiocytes.
• The epidermis and adnexae are uninvolved, in contrast to lymphoma.
• Mitotic figures are rare, except in germinal centers.
• The B-cells stain for the usual B-cell markers (CD20, CD19. CD79a) and are polytypic for immunoglobulin light chains (kappa and lambda).  They are usually surrounded by numerous CD3+ T-cells.

Cases associated with this book:

B-cell pseudolymphoma
Author: Stephen Lyle, M.D., Ph.D.

Conference: DermatopathologyConsultations.com Teaching Collection