SHM Converge Scientific Abstract ePoster Gallery-The Unintended Consequence: T-Cell Lymphoma of the Small Intestine Following Car-T Cell Therapy

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This case report describes a rare secondary malignancy after CAR T-cell therapy: indolent T-cell lymphoma of the small intestine.<br /><br />A 55-year-old woman with long-standing, treatment-refractory multiple myeloma achieved complete remission after CAR T-cell therapy in December 2024. Three months later, she developed persistent high-volume watery diarrhea (5–6 episodes daily), profound weight loss of 40 pounds, and severe electrolyte abnormalities. An extensive evaluation excluded infectious, autoimmune, and malabsorptive causes. Symptomatic treatments such as loperamide, octreotide, pancrelipase, diphenoxylate-atropine, and opioid tincture provided little benefit.<br /><br />Endoscopic workup was initially unrevealing. EGD showed chronic duodenitis with increased intraepithelial atypical lymphocytes but no definitive malignancy, and colonoscopy was normal. Because symptoms worsened, small-bowel enteroscopy with biopsy was performed. Histology demonstrated lamina propria expansion by predominantly small mature lymphocytes with minimal mitotic activity. Immunophenotyping showed CD3 positivity, CD8 predominance, weak/negative CD4, and negativity for CD56, CD57, perforin, granzyme B, and CD20, with low Ki-67 activity. These findings were consistent with indolent T-cell lymphoma of the gastrointestinal tract.<br /><br />The report emphasizes that while CAR T-cell therapy is an important treatment for relapsed/refractory multiple myeloma, it can be associated with rare secondary malignancies, including T-cell lymphoma. GI-predominant presentations may mimic more common conditions such as infection or inflammation, delaying diagnosis. The case also highlights the unusually short interval—within six months of CAR T-cell treatment—between therapy and lymphoma development.<br /><br />Overall, the authors call for continued research to better define the risk, timing, outcomes, and management of secondary cancers after CAR T-cell therapy.

Asset Subtitle

Kanza Maqsood

Meta Tag

Author List Amna Naveed Butt, Anjum Dhamani, Daniel Davila Gonzalez, Kanza Maqsood, Sabita Ale Thapa, Scott M. Keeney

Category Clinical Vignettes

Concept CAR-T Therapy

Concept Secondary T-Cell Lymphoma

Concept Small Intestinal Lymphoma

Concept Secondary Malignancy

Concept Gastrointestinal Tract

Distinguished Non-Finalist

Presenter Organization Texas Health Resources HEB/Denton Internal Medicine Residency

Presenting Author Kanza Maqsood

Track Adult

Keywords

CAR T-cell therapy

secondary malignancy

indolent T-cell lymphoma

small intestine

multiple myeloma

watery diarrhea

gastrointestinal lymphoma

enteroscopy biopsy

CD3 positive

weight loss

CAR-T Therapy

Secondary T-Cell Lymphoma

Small Intestinal Lymphoma

Secondary Malignancy

Gastrointestinal Tract