Clinical Features:

• Recurrent red to brown papules or plaques
• Most common on the upper extremities and trunk
• Possible association with Borrelia burgdorferi infection
• Excellent prognosis

Histologic Features:

• Nodular to diffuse lymphocytic infiltrate involving the dermis and upper subcutaneous fat
• The infiltrate is composed of small mature lymphocytes and monocytoid B-cells.
• Monocytoid B-cells are medium-sized lymphocytes with abundant clear-staining cytoplasm and indented nuclei.
• Reactive germinal centers are frequently present, and the neoplastic lymphocytes commonly encroach on the germinal centers.
• Focal to extensive plasma cell differentiation is common.
• The epidermis is characteristically spared.
• The immunophenotype is nonspecific, with positivity for pan-B-cell markers.
• If plasmacytic differentiation is present, immunohistochemical staining for immunoglobulin light chains may demonstrate kappa or lambda light chain restriction, proving the clonal nature of the process.

Cases associated with this book:

Primary cutaneous marginal zone B-cell lymphoma
Author: Stephen Lyle, M.D., Ph.D.

Conference: Dr. Z's Consultations

Primary cutaneous marginal zone B-cell lymphoma
Author: Stephen Lyle, M.D., Ph.D.

Conference: DermatopathologyConsultations.com Teaching Collection

88-year-old man with red-purple plaques on chest and face and a history of Waldenstrom's macroglobulinemia
Author: Artur Zembowicz M.D. Ph.D.

Conference: Dr. Z's Consultations