Unilateral Renal Castleman Disease Presenting with Acute Abdominal Pain: A Case Report and Literature Review

Castleman disease (CD) is a rare lymphoproliferative disorder, with primary renal involvement being exceptionally uncommon. Most cases are asymptomatic and discovered incidentally. This report describes an unusual presentation of renal CD manifesting as acute abdominal pain, highlighting the diagnostic challenges in differentiating it from renal malignancies.

A 55-year-old Chinese female presented to the emergency department with sudden-onset epigastric pain radiating to the left lumbar region, accompanied by nausea and vomiting. Emergency CT revealed a left renal mass measuring 80 × 75 mm with internal nodular calcifications. Contrast-enhanced CT demonstrated heterogeneous enhancement patterns suspicious for chromophobe renal cell carcinoma. Laboratory tests showed elevated transaminases and microscopic hematuria. Given the inability to exclude malignancy, the patient underwent laparoscopic left nephrectomy. Histopathological examination revealed hyaline vascular Castleman disease with characteristic “onion-skin” lymphoid follicles, atrophic germinal centers, and “lollipop-like” vascular structures. Immunohistochemistry confirmed mixed B- and T-cell proliferation without evidence of monoclonality. The patient recovered uneventfully, with complete symptom resolution.

This case emphasizes that CD should be considered in the differential diagnosis of renal masses, particularly those with unusual enhancement patterns and calcifications. While definitive diagnosis relies on histopathology, recognition of this entity may guide appropriate surgical planning and avoid unnecessary radical procedures. The excellent prognosis following complete excision underscores the importance of accurate diagnosis.