Journal of Hematopathology

Transdifferentiation of diffuse large B-cell lymphoma to a poorly differentiated neoplasm following CAR T-cell therapy

Chimeric antigen receptor T-cell (CAR-T) therapy is a recent advancement in precision medicine with promising results for patients with relapsed or refractory B-cell malignancies. However, rare post-therapy morphologic, immunophenotypic, and genomic alterations can occur. This study is to present a case of a patient with diffuse large B-cell lymphoma (DLBCL) who underwent anti-CD19 CAR-T therapy with disease in the uterus that showed transdifferentiation to a poorly differentiated malignant neoplasm that failed to express any lineage specific markers. In immunohistochemistry, fluorescence in situ hybridization (FISH) and targeted next-generation sequencing (NGS) were utilized to fully characterize the diagnostic DLBCL sample in comparison to the poorly differentiated neoplasm of the uterus. Analysis of the diagnostic DLBCL and the poorly differentiated neoplasm demonstrated evidence of a clonal relationship as well as revealing acquisition of mutations associated with CAR-T resistance. Furthermore, downregulation of B-cell associated antigens was observed, underscoring a mechanistic link to CAR-T evasion as well as demonstrating diagnostic confusion. This case illustrates the utility of employing multiple diagnostic modalities in elucidating a pathologic link between a B-cell lymphoma and poorly differentiated neoplasm following targeted therapy.

CD8-positive T-cell lymphoproliferative disorder of the uterus: a new subtype of indolent extranodal T-cell neoplasm?

A 51-year-old female with menorrhagia was found to have a cervical polyp. Polypectomy and endometrial curettage showed an atypical lymphoid infiltrate. Hysterectomy was performed, showing extensive myometrial infiltration by small, cytologically bland CD3-positive αβ T cells with a non-activated cytotoxic phenotype and a low proliferative rate. PCR showed clonal TCR-β gene rearrangement. Lymph nodes were uninvolved. PET-CT was negative. A diagnosis of CD8-positive T-cell lymphoproliferative disorder (T-LPD) was made. At 6 months, the patient was asymptomatic with a negative repeat PET-CT. A critical recent advance in the classification of lymphoid neoplasms is the recognition of indolent extranodal T-LPDs, including those of the gastrointestinal tract (T-cell and NK-cell types) and skin (small/medium CD4-positive and acral CD8-positive). However, T-LPDs of the uterus are rare. Two indolent T-LPDs of the uterus have been reported, both showing a CD8-positive, nonactivated cytotoxic phenotype, low proliferative rate, and clonal TCR rearrangement. Neither developed systemic disease nor recurrence. The etiology of indolent T-LPDs and their relationship to overt T-cell lymphomas remain poorly understood. T-LPDs of the uterus may arise from effector memory T-cells that establish long-term, tissueresident immunologic memory following exposure to fetal extravillous trophoblastic cell alloantigens during a previous pregnancy. Neither our patient nor the 2 previously reported had a current pregnancy or a known recent infection or toxic exposure, and the event(s) triggering evolution into T-LPD are unknown. Indolent T-LPDs can be encountered at new and unusual extranodal sites; knowledge of their clinicopathological features will help avoid unnecessary cytotoxic chemotherapy and improve understanding of this group of disorders.

A case of transient monoclonal plasma cell aberrancy following respiratory syncytial virus (RSV) vaccination

Plasma cell neoplasms include a spectrum of disorders ranging from monoclonal gammopathy of undetermined significance to multiple myeloma, defined by clonal plasma cell proliferation and production of monoclonal immunoglobulins. However, transient monoclonal plasma cell expansions without neoplastic features are rarely documented. Herein, we report a 77-year-old female patient with a history of stage IVa high-grade serous carcinoma of the ovary who was found to have leukocytosis and 22% circulating monoclonal plasma cells during routine preoperative testing, 4 days after receiving the RSV vaccine. Flow cytometry demonstrated lambda-restricted plasma cells expressing CD19+, CD27+, CD38+, CD56-, and CD138+. Serum protein electrophoresis and immunofixation were unremarkable, with a normal κ/λ ratio and absence of M-protein. Repeat flow cytometry 6 days later revealed normalization to polyclonal plasma cells. No clinical or biochemical evidence supported a plasma cell neoplasm, and bone marrow biopsy was postponed. This case underscores the need for clinical awareness of post-vaccination immunologic phenomena that may mimic plasma cell neoplasm. Recognition of such transient aberrancies can prevent unnecessary invasive investigations and broaden understanding of vaccine-induced immune dynamics.

Anaplastic large cell lymphoma presenting as a mass in the uterine cervix: a case report

T-cell lymphoma is an extremely rare form of malignancy in the female genital tract. Most of the reported cases of lymphoma are B-cell lymphomas. A few cases of primary T-cell lymphomas involving the vagina or the vulva have been reported. We are reporting the first case of anaplastic large cell lymphoma (ALCL) presenting as a uterine cervical mass. The patient is a 24-year-old female who presented to the emergency room with a history of menorrhagia, night sweats and 40-pound weight loss. The diagnosis of ALCL was confirmed through immunohistochemical studies with strong CD30 and ALK expression. Fluorescent hybridization showed a rearrangement of the anaplastic lymphoma kinase (ALK) gene. Since ALCL may have a variable expression of T-cell antigens, the diagnosis may easily be missed when CD45 and/or CD3 is negative, and screening epithelial stains for carcinoma (e.g., p63 and EMA) are positive. CD30 must be performed to raise the consideration of ALCL when reniform nuclei are observed.