Epidermotropic marginal zone lymphoma simulating mycosis fungoides^†

Abstract

Cutaneous lymphomas can usually be distinguished by architectural features, where most atypical lichenoid infiltrates implicate cutaneous T-cell lymphoma (CTCL). We report a case of an 80-year-old man who presented with asymptomatic golden brown patches and diffuse pink papules on his trunk, buttocks and hips. Biopsies revealed a lichenoid infiltrate and areas of epidermotropism. Although the overall architectural pattern was compatible with mycosis fungoides, the lymphocytes had a more monocytoid and plasmacytoid appearance, and there were interspersed mature plasma cells. Immunohistological studies revealed that the pleomorphic lymphocytes were predominantly B cells (CD20\+ and CD79a\+) with a subpopulation of smaller bland T cells (CD3\+). Moreover, the B-cell immunophenotype was compatible with marginal zone differentiation (bcl-2+, bcl-6-, CD10- and CD5-) and showed a lambda light chain restriction, confirming monoclonality. These findings were diagnostic for cutaneous marginal zone B-cell lymphoma (MZL) with epidermotropism an entity which has only been reported twice in the literature, once in the setting of primary cutaneous disease, and once as cutaneous involvement of systemic disease. This case illustrates a rare pattern of cutaneous MZL, and underscores the importance of immunophenotypic characterization of cutaneous lymphomas in order to prevent the misdiagnosis of a CTCL.

Epidermotropic B-Cell Lymphoma

“…[9][10][11][12][13] The paraffin-embedded samples of the 2 hospital database cases were examined by routine hematoxylin and eosin (HE) followed by selective phenotypic studies to assess the expression of CD2, CD3, CD4, CD5, CD10, CD20, CD30, CD79a, CD14, CD83, CD11c, CD56, PAX5, CD23, BCL-2, BCL-6, P16, TCL1 oncogene, lysozyme, myeloperoxidase, IgG, IgM, IgG4, kappa, lambda, and MUM1. Two cases were encountered in the hospital database, whereas 5 cases have been previously reported.…”

“…Material was received on 3 available previously reported cases [10][11][12] to examine the routine HE stain followed by PAX5 and CXCR3 immunostain.…”

“…Lee et al 12 reported another case in 2013, an 80-yearold man with no significant medical history presented with a 2-week history of asymptomatic golden-brown patches and diffuse pink papules on the trunk, buttocks, hips, and thighs. Although the biopsy showed an overall architectural pattern compatible with MF, phenotypic studies revealed a B-cell lymphoma with marginal zone differentiation.…”

“…[10][11][12] All 3 cases showed vacuolar interface dermatitis accompanied by a band-like lymphocytic infiltrate with focal epidermotropism (Figs. [10][11][12] All 3 cases showed vacuolar interface dermatitis accompanied by a band-like lymphocytic infiltrate with focal epidermotropism (Figs.…”

“…There are only 6 reports of epidermotropic B-cell neoplasm in the human literature, [9][10][11][12][13][14] all in the context of anecdotal case reports (Table 1). There was papillary dermal mucin deposition accompanied by edematous change.…”