. Recurrences may occur. Rarely, lymph nodes, the gastrointestinal system, lung, bone and bone marrow may be involved as extracutaneous sites.
Primary cutaneous B-cell lymphomas account for approximately 25% of all cutaneous lymphomas. Clinically, patients present with either solitary or multiple papules or plaques, typically on the upper extremities or trunk.
Histopathology is vital for the correct diagnosis. In this patient, the histologic report was written as follows: “The findings are those of a well-differentiated but atypical diffuse mixed small lymphocytic infiltrate representing a mixture of T-cells and B-cells. The minor component of the infiltrate is of T-cell lineage, whereby the cells do not show any phenotypic abnormalities. The background cell population is interpreted as reactive. However, the dominant cell population is in fact of B-cell lineage. It is extensively highlighted by CD20. Only a minor component of the B cell infiltrate appeared to be in the context of representing germinal centers as characterized by small foci of centrocytic and centroblastic infiltration highlighted by BCL6 and CD10. The overwhelming B-cell component is a non–germinal center small B cell that does demonstrate BCL2 positivity and significant immunoreactivity for CD23. This small lymphocytic infiltrate obscures the germinal centers. There are only a few plasma cells; they do not show light chain restriction.”
The pathologist remarked that “this type of morphology of a diffuse small B-cell lymphocytic infiltrate that is without any evidence of light chain restriction amidst plasma cells, whereby the B cell component is dominant over the T-cell component would in fact be consistent with a unique variant of marginal zone lymphoma derived from a naive mantle zone.”
Dr. Donna Bilu Martin
PCMZL has an excellent prognosis. When limited to the skin, local radiation or excision are effective treatments. Intravenous rituximab has been used to treat multifocal PCMZL. This patient was found to have no extracutaneous involvement and was treated with radiation.
This case and photo were submitted by Dr. Bilu Martin.
Dr. Bilu Martin is a board-certified dermatologist in private practice at Premier Dermatology, MD, in Aventura, Fla. More diagnostic cases are available at mdedge.com/dermatology. To submit a case for possible publication, send an email to dermnews@mdedge.com.
References
Virmani P et al. JAAD Case Rep. 2017 Jun 14;3(4):269-72.
Magro CM and Olson LC. Ann Diagn Pathol. 2018 Jun;34:116-21.