Rare Case: Renal Sarcoidosis with Parotid and Uterine Complications

The recent case study published in BMC Nephrology reported the first case of renal sarcoidosis complicated by parotid glands and uterus lesions. Pathological findings and the reactivity in Ga scintigraphy indicated the lesions' presence in these organs.

Sarcoidosis is a systemic condition capable of impacting various organs. While pulmonary involvement is the most prevalent, renal manifestations are less common. Hirotaka Fukasawa, Iwata City Hospital, Iwata, Shizuoka, Japan, and colleagues reported a case of sarcoidosis with an exceptionally rare distribution, including renal lesions.

The case concerns a 51-year-old Japanese woman who was referred to the hospital due to bilateral parotid swelling and renal dysfunction without a history of previous renal issues. On physical examination, she exhibited bilateral parotid swelling, and lower leg edema, and reported hypermenorrhea. Laboratory tests revealed elevated serum creatinine (3.1 mg/dL), serum corrected calcium (10.6 mg/dL), serum angiotensin-converting enzyme (ACE) levels (44.9 U/L), and lysozyme levels (75 µg/mL). Urinary β2-microglobulin (β2-MG) levels were also elevated. Computed tomography (CT) scans showed swelling in both kidneys, parotid glands, and the uterus, confirmed by Ga scintigraphy, which revealed significant accumulation in these organs. Ocular screening for uveitis was negative.

During hospitalization, needle aspiration cytology of the parotid gland and endometrial cytology confirmed the presence of epithelioid cells indicative of sarcoidosis. Renal biopsy revealed tubulointerstitial nephritis with diffuse non-caseating epithelioid cell granulomas and multinucleated giant cells infiltrating the interstitial area and renal tubules. Immunohistochemical staining, including CD68, showed positive results in macrophages. Staining for 1-α hydroxylase (CYP27B1) and lysozyme also displayed remarkable positivity in multinucleated giant cells, and infiltrating cells, consistent with renal sarcoidosis diagnosis with parotid gland and uterine involvement.

Treatment commenced with prednisolone at 40 mg/day (0.8 mg/kg/day) from the 11th day of admission, resulting in rapid improvement of renal function, hypercalcemia, and reductions in urinary β2-MG, serum ACE, serum lysozyme, and serum 1,25(OH)2 vitamin D3 levels. A follow-up Ga scintigraphy showed the resolution of the previous organ accumulations. The patient was discharged on the 53rd day with a stable condition and maintained serum ACE levels within the normal range (7.2–18.4 U/L) for at least 30 months post-treatment.

In conclusion, the researchers documented a novel case of renal sarcoidosis with complications involving the parotid glands and uterus, an exceptionally rare distribution of lesions in sarcoidosis. Additionally, staining for 1-α hydroxylase and lysozyme revealed positive results in infiltrating cells, likely macrophages within renal granulomas. The presence of 1-α hydroxylase in these cells suggests a potential mechanism for hypercalcemia, while lysozyme positivity may serve as a supportive diagnostic marker for sarcoidosis in future cases.

Reference:

Kitamoto, S., Kaneko, M., Omata, K. et al. A case of renal sarcoidosis complicated by parotid gland and uterine lesions. BMC Nephrol 25, 198 (2024). https://doi.org/10.1186/s12882-024-03635-6