The Conundrum of Diagnosing Cutaneous Composite Lymphoma in the Molecular Age

Epstein-Barr Virus Positive Diffuse Large B-Cell Lymphoma with Epidermotropism

Primary cutaneous B-cell lymphomas are rare diseases comprising nodular to diffuse lymphoid cell infiltration with an overlying grenz zone and no epidermal involvement upon histological analysis. Diagnostics can become challenging when lymphomas exhibit the characteristics of both B and T-cells. Differential diagnoses may include reactive proliferations, cutaneous composite lymphomas, and transformed mycosis fungoides. Immunohistochemistry and gene arrangement tests may be beneficial to clarify the diagnosis. Herein, we report a rare case of epidermotropic EBV-positive cutaneous B-cell lymphoma along with a literature review.

Concurrent Presentation of Mycosis Fungoides and Primary Cutaneous Marginal Zone LPD: Clinicopathological Study of 4 Cases and Literature Review

BACKGROUND

Mycosis fungoides is rarely associated to B-cell malignancies, and the few reported cases are mainly internal lymphomas involving secondarily the skin (ie, chronic lymphocytic leukemia).

OBJECTIVES

The aim of our study is to describe the clinical and histopathological features of 4 patients presenting with 2 concurrent primary cutaneous lymphomas and review the pertinent literature.

METHODS

We identified 4 cases of concurrent primary cutaneous lymphomas in our institutions. An extracutaneous lymphoma was ruled out on the basis of a complete work out. We performed a PubMed search to identify reported cases of primary cutaneous composite or concurrent lymphomas.

RESULTS

Eleven cases of primary cutaneous concurrent lymphomas have been described in the literature. Counting all together (our cases and the cases previously described in the literature), mycosis fungoides was the most frequent primary cutaneous T-cell lymphoma (TCL) (13/15), followed by 1 case of peripheral TCL-NOS and 1 case of subcutaneous panniculitis-like TCL. Regarding the associated primary cutaneous B-cell lymphomas, 8/15 cases consisted of low-grade B-cell lymphomas [that is, 5 marginal zone lymphoma (in the most recent classification reclassified as marginal zone lymphoproliferative disorder, MZLD, 2 follicular-center B-cell lymphoma (primary cutaneous follicle-center lymphoma) and 1 low-grade NOS B-cell lymphoma]; 4/15 were associated to Epstein-Barr virus; 1 case consisted of a methotrexate-associated lymphoproliferative disease, and 2 cases consisted of primary cutaneous diffuse large B-cell lymphoma-leg type.

CONCLUSIONS

Primary cutaneous concurrent lymphomas are exceptional. Clinicopathological correlation and a complete workout to reach the correct diagnosis may guide the appropriate treatment in each case.

Primary Cutaneous B-Cell Lymphoma Complicated by Clonal T-Cell Populations: A Diagnostic Dilemma

ABSTRACT

Cutaneous lymphomas, both B-cell and T-cell, are not uncommonly seen in the skin, but those lymphomas exhibiting clonality for both B-cell and T-cell populations are scarce. Characterization of dual receptor rearrangement as primary composite lymphoma versus primary lymphoma with reactionary response is complex and often a challenge that goes unrecognized. In this study, we report a unique case of T-cell gene rearrangement positivity complicating the diagnosis of primary cutaneous low-grade B-cell lymphoma along with a review of reported cases containing dual receptor rearrangement to identify trends among final diagnostic decisions. As one might guess, for cutaneous lymphomas presenting with clonality for both T-cell and B-cell receptors, diagnosis can be difficult and confusing because the differential is broad. The literature suggests the majority of these cases may be cutaneous composite lymphomas. However, immunohistochemical, clinical, and histomorphologic features must all be assessed for an accurate diagnosis, which is critical for proper prognosis and therapy.

Single-cell RNA sequencing profiling in a patient with discordant primary cutaneous B-cell and T-cell lymphoma reveals micromilieu-driven immune skewing

BACKGROUND

Primary cutaneous lymphomas comprise a heterogeneous group of B-cell and T-cell malignancies which often show an indolent course, but can progress to aggressive disease in a subset of patients. Diagnosis is often delayed owing to clinical and histopathological similarities with benign inflammatory conditions. Especially during early disease, cancer cells are present at relatively low percentages compared with the inflammatory infiltrate, an interplay that is currently only insufficiently understood.

OBJECTIVES

To improve diagnostics and perform molecular characterization of a complex type of primary cutaneous lymphoma.

METHODS

Single-cell RNA sequencing (scRNA-seq) was performed and combined with T-cell and B-cell receptor sequencing.

RESULTS

We were able to diagnose a patient with concurrent mycosis fungoides (MF) and primary cutaneous follicle centre lymphoma (PCFCL), appearing in mutually exclusive skin lesions. Profiling of tumour cells and the tissue microenvironment revealed a type-2 immune skewing in MF, most likely guided by the expanded clone that also harboured upregulation of numerous pro-oncogenic genes. By contrast, PCFCL lesions exhibited a more type-1 immune phenotype, consistent with its indolent behaviour.

CONCLUSIONS

These data not only illustrate the diagnostic potential of scRNA-seq, but also allow the characterization of specific clonal populations that shape the unique tissue microenvironment in clinically distinct types of lymphoma skin lesions.

Cutaneous composite lymphoma of mycosis fungoides and Hodgkin lymphoma: Response to sequential therapy

Composite lymphoma is defined as two or more morphologically and immunophenotypically distinct lymphoma clones that occur in the same tissue site. The occurrence of cutaneous composite lymphoma (CCL) is extremely rare. Here we report a unique case of CCL consisting of Hodgkin lymphoma (HL) and mycosis fungoides (MF). Our patient presented with longstanding erythematous plaques on the skin and later developed axillary lymph node enlargement. Histopathologically, the skin lesions were characterized by a dense dermal lymphocytic infiltrate with prominent epidermotropism of pleomorphic T-cells, consistent with typical MF. Nonetheless, scattered large atypical cells resembling Reed-Sternberg (R-S) cells were interspersed among these atypical T-cells in the deep dermis. Immunophenotyping suggested a HL origin of these R-S cells. Monoclonality of T-cell receptor beta gene was detected in the skin, monoclonal immunoglobulin heavy chain gene rearrangement was identified in these R-S cells microdissected from the deep dermis, confirming the origin from HL. The lymph node biopsy showed nodular sclerosis classic Hodgkin lymphoma. Therefore, CCL of HL and MF, with lymph node HL was diagnosed. The lesions of this patient responded to a sequential treatment to HL and MF. Being aware of this rare CCL facilitates correct diagnosis and proper clinical management.