Lipomatosis Mimics Disease: Ultrasound Unmasks Rare Benign Node Change in Cat

Ultrasonographic Findings of Jejunal Lymph Node Lipomatosis in a Cat: A Case Report

Michał Gruss, Anna Lukomska, Maciej Gogulski, Roland Kozdrowski

Background:
Lymph node lipomatosis (LNL)—the replacement of lymphoid tissue by adipocytes—is recognized in human and laboratory animal pathology but has not been previously described in companion animals. Ultrasonographic identification of hyperechoic jejunal lymph nodes (JLNs) may represent a benign form of lipomatosis rather than inflammatory or neoplastic disease. This case report aimed to correlate sonographic findings with histopathology in a cat with suspected LNL.

Methods:
A 16-year-old neutered female European Shorthair cat with chronic kidney disease (stage II) and suspected hepatic lipidosis underwent abdominal ultrasound, revealing uniformly hyperechoic JLNs with thin hypoechoic peripheral rims. Power Doppler interrogation showed no vascularization. Two years later, the cat was euthanized for end-stage kidney disease, and jejunal lymph nodes were re-examined via ultrasound and histology. Histopathological evaluation included H&E and Oil Red O staining to confirm adipose tissue infiltration.

Results:
Postmortem ultrasound confirmed unchanged hyperechoic JLNs. Macroscopic evaluation showed JLNs embedded in mesenteric fat. Histologically, adipocyte infiltration replaced the lymphoid parenchyma, with residual thin subcapsular lymphoid tissue rim and peri-adipocyte lymphocyte cuffing. Oil Red O staining confirmed neutral lipid accumulation. No evidence of inflammation or neoplasia was found. Findings were consistent with benign lymph node lipomatosis. The cat’s history of suspected lipid metabolism dysfunction (hepatic lipidosis) and old age supported parallels with human cases.

Limitations:
This was a single case report, limiting generalizability. No other lymph nodes were evaluated, and no functional immune testing was performed. The distinction between hilar fat and early lipomatosis remains unclear, necessitating cautious interpretation of similar sonographic findings.

Conclusions:
Jejunal lymph node lipomatosis can occur in cats, presenting sonographically as hyperechoic lymph nodes with thin hypoechoic rims. Awareness of LNL as a benign differential diagnosis may improve diagnostic accuracy and prevent unnecessary interventions in feline patients. Further studies are needed to assess its prevalence, pathogenesis, and clinical significance.

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