Pseudoneoplastic Fat Atrophy of Intra-Abdominal Sites: A Clinicopathologic Study of 16 Cases Representing a Potential Diagnostic Pitfall

Suster DI, Gross JM, Kallen M, Gonzalez RS, Salviato T, Agaimy A, Michal M, Carneiro AM, Waters KM (2026)

Publication Type: Journal article

Publication year: 2026

Journal

American Journal of Surgical Pathology Lippincott, Williams & Wilkins

Book Volume: 50

Pages Range: 317-325

Journal Issue: 3

DOI: 10.1097/PAS.0000000000002495

Abstract

Patients undergoing periods of starvation or malnutrition may develop degenerative and/or atrophic changes of various organs. These findings may manifest histologically and may cause confusion when first encountered, raising a differential that includes benign and malignant tumor entities. Herein, we report 16 cases of incidentally identified degenerative changes within abdominal-site fatty tissues that caused diagnostic difficulties. The patients were 11 males and 5 females, aged from 1 day to 82 years (mean: 58 years). The degenerative changes were all incidentally identified within adipose tissue of the abdominal cavity or adjacent to organs contained within the abdominal cavity in procedures done for unrelated reasons such as cancer, infection, or perforation. Cases were identified in the colon (n=6), small intestine (n=4), omentum (n=3), inguinal hernia sac (n=1), peritoneum (n=1), and retroperitoneal soft tissue (n=1). Patients had variable past medical histories with multiple comorbidities. Ten patients presented with some form of malnutrition and/or cachexia. Histologically, the lesions demonstrated lobules of atrophic-appearing fat with small signet-ring-like adipocytes that were sometimes bilobed. The nodules varied in size and were characterized in some cases by a variably myxoid stromal background, often with a prominent delicate capillary network. Immunohistochemistry was performed and was uniformly positive for S100 protein and negative for cytokeratins. The lesions were generally recognized as degenerative, but various differential diagnoses proposed at the time of sign-out included signet-ring cell carcinoma, liposarcoma, and vascular lesions, among others. Nomenclature to describe this phenomenon has been inconsistent in the literature, and thus, we suggest the term "pseudoneoplastic fat atrophy."

Authors with CRIS profile

Abbas Agaimy Institute of Pathology

Involved external institutions

Rutgers, The State University of New Jersey US United States (USA) (US) Johns Hopkins Hospital US United States (USA) (US) University of Maryland, College Park (UMD) US United States (USA) (US) Emory University US United States (USA) (US) Istituto Nazionale Tumori IRCCS "Fondazione G. Pascale" IT Italy (IT) Fakultní Nemocnice Plzeň CZ Czech Republic (CZ) Lab Pat – Pathological Analysis Laboratory / Laboratório de Anatomia Patológica BR Brazil (BR) Cedars-Sinai Medical Center US United States (USA) (US)

How to cite

APA:

Suster, D.I., Gross, J.M., Kallen, M., Gonzalez, R.S., Salviato, T., Agaimy, A.,... Waters, K.M. (2026). Pseudoneoplastic Fat Atrophy of Intra-Abdominal Sites: A Clinicopathologic Study of 16 Cases Representing a Potential Diagnostic Pitfall. American Journal of Surgical Pathology, 50(3), 317-325. https://doi.org/10.1097/PAS.0000000000002495

MLA:

Suster, David I., et al. "Pseudoneoplastic Fat Atrophy of Intra-Abdominal Sites: A Clinicopathologic Study of 16 Cases Representing a Potential Diagnostic Pitfall." American Journal of Surgical Pathology 50.3 (2026): 317-325.

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