From the Journals

Atypical case of cutaneous MCL mimics SPTCL


 

FROM JOURNAL OF CUTANEOUS PATHOLOGY

An atypical case of cutaneous mantle cell lymphoma (MCL) with histomorphological features mimicking subcutaneous panniculitis-like T-cell lymphoma (SPTCL) highlights a “potential pitfall,” according to investigators.

This unusual case stresses the importance of molecular cytogenetics and/or immunohistochemistry for panniculitis-type lymphomas, reported lead author Caroline Laggis, MD of the University of Utah, Salt Lake City, and colleagues.

“While morphologic features of SPTCL, specifically rimming of adipocytes by neoplastic lymphoid cells, have been documented in other types of lymphomas, this case is exceptional in that the morphologic features of SPTCL are showed in secondary cutaneous involvement by MCL,” the investigators wrote. Their report is in Journal of Cutaneous Pathology.

The patient was a 69-year-old man who presented with 2-year history of night sweats and fever of unknown origin, and, closer to presentation, weight loss and tender bumps under the skin of his pelvic region.

Subsequent computed tomography and excisional lymph node biopsy led to a diagnosis of MCL, with a Mantle Cell Lymphoma International Prognostic Index of 5, suggesting aggressive, intermediate-risk disease. Further imaging showed involvement of the nasopharynx, and cervical and mediastinal lymph nodes.

Bendamustine and rituximab chemotherapy was given unremarkably until the final cycle, at which point the patient presented with tender subcutaneous nodules on his lower legs. Histopathology from punch biopsies revealed “a dense infiltrate of monomorphic, mitotically active lymphoid cells with infiltration between the deep dermal collagen and the adipocytes in subcutaneous fat,” the investigators wrote, noting that the infiltrative cells were blastoid and 70% expressed cyclin D1, supporting cutaneous involvement of his systemic MCL.

Treatment was switched to ibrutinib and selinexor via a clinical trial, which led to temporary improvement of leg lesions; when the lesions returned, biopsy was performed with the same histopathological result. Lenalidomide and rituximab were started, but without success, and disease spread to the central nervous system.

Another biopsy of the skin lesions again supported cutaneous MCL, with tumor cells rimming individual adipocytes.

Because of this atypical morphology, fluorescence in situ hybridization (FISH) was conducted, revealing t(11;14)(q13:32) positivity, thereby “confirming the diagnosis of cutaneous involvement by systemic MCL,” the investigators wrote.

Genomic sequencing revealed abnormalities of “ataxia-telangiectasia mutated, mechanistic target of rapamycin kinase (mTOR), BCL6 corepressor, and FAS-associated factor 1, as well as the expected mutation in IGH-CCND1, leading to cyclin D1 upregulation.”

Subsequent treatment was unsuccessful, and the patient died from his disease.

“The complex and central role that mTOR plays in adipose homeostasis may link our tumor to its preference to the adipose tissue, although further investigation is warranted regarding specific genomic alterations in lymphomas and the implications these mutations have in the involvement of tumor cells with cutaneous and adipose environments,” the investigators wrote.

The investigators did not report conflicts of interest.

SOURCE: Laggis C et al. 2019 Apr 8. doi:10.1111/cup.13471.

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