Cutaneous Small/Medium CD4+ Pleomorphic T-Cell Lymphoma-Like Nodule in a Patient With Erythema Chronicum Migrans

Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder in children: A case report and review of the literature

Primary cutaneous CD4⁺ small/medium T-cell lymphoproliferative disorder (PCSM-TCLPD) is a rare benign lymphoproliferative disorder, recently redefined by the 2016 World Health Organization classification of lymphoid neoplasms. In adults, PCSM-TCLPD responds well to monotherapy with surgical excision or local radiation, with or without topical/injected corticosteroids; in contrast, PCSM-TCLPD has only rarely been reported in children, in whom treatments favored in adults may be non-optimal. We present a 14-year-old male with PCSM-TCLPD on the forehead, who achieved complete remission following biopsy, topical corticosteroids, and surgical excision. We also review all literature-reported cases of pediatric PCSM-TCLPD, emphasizing the disorder's benign nature and treatment responsiveness in children.

Prominent Blasts in Primary Cutaneous CD4+ Small/Medium T-Cell Lymphoproliferative Disorder. A Reconsideration of Diagnostic Criteria

ABSTRACT

Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder (PCSM-LPD), recently downgraded from a T-cell lymphoma, is a poorly characterized histopathological entity. Presenting as a solitary lesion that often grows rapidly, it may raise suspicion for a cutaneous B-cell lymphoma. However, classically, the dermal lymphoid proliferation is predominantly CD4+ with a follicular T-helper profile and a smaller B-cell fraction. Diagnostic uncertainty may arise when B cells are present in large numbers, a B-cell clone is present, or large cell populations are seen. To meet the diagnostic criterion of PCSM-LPD, large cells should not constitute more than 30% of the infiltrate. The 2 cases presented in this article caused diagnostic uncertainty owing to the observation of high numbers of large cells and in one case the presence of a B-cell clone, on the background of otherwise typical clinicopathological features of PCSM-LPD. We review the literature specifically regarding the prevalence of large cell populations and their immunophenotypic characteristics and in light of this discuss whether a current diagnostic criterion should be reconsidered.

Primary Cutaneous CD4+ Small/Medium T-Cell Lymphoproliferative Disorder or Primary Cutaneous Marginal Zone B-Cell Lymphoma? Two Distinct Entities With Overlapping Histopathological Features

ABSTRACT

Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder and primary cutaneous marginal zone B-cell lymphoma are 2 distinct entities with several overlapping features which can result in diagnostic uncertainty. Clinically, they both follow an indolent course and present with solitary or multiple papules or nodules. Histologically, they are characterized by polymorphous dermal infiltrates rich in mixed populations of B cells and T cells, often in similar proportions. The histological hallmark of primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder is the presence of follicular T-helper cells within the infiltrate and has historically been used as a marker for differentiating between the 2 conditions. However, there is now mounting evidence that follicular T-helper cells are also seen in primary cutaneous marginal zone B-cell lymphoma and nodal marginal zone lymphoma. The 2 cases presented herein caused diagnostic uncertainty because they displayed appreciable features of both conditions. We discuss the potential mechanisms behind these overlapping histopathological features and hypothesize a model that explores the idea of a collective organoid response to an antigenic stimulus.