This retrospective series included 9 male patients diagnosed with acquired cystic kidney disease (ACKD) from the Department of Pathology, Peking University Third Hospital between 2020 and 2025. Patient ages ranged from 29 to 64 years. Underlying causes of end-stage renal disease (ESRD) were listed as hypertension, IgA nephropathy, chronic glomerulonephritis, and diabetes. Duration of dialysis spanned 1 to 30 years with a median of 9.0 years. Three patients had a history of kidney transplantation. Of the 9 patients, 7 had concurrent renal cell carcinoma (RCC).
Radiologic assessment consistently demonstrated reduced kidney size with multiple renal cysts; some cysts were described as complex. In 5 of the 7 RCC cases, solid nodular lesions were identified in the cyst wall. One post-transplant patient had a solid lesion identified in the native kidney by ultrasound. Tumor maximum diameters ranged from 1.3 to 7.0 cm, with a median size of 3.0 cm.
All cases showed the characteristic morphological changes of ACKD. Atypical renal cysts were observed in every case, regardless of whether a secondary tumor was present. Among the tumors, six were diagnosed as ACKD-associated RCC (ACKD-RCC) and one as papillary RCC (pRCC).
Most ACKD-RCC tumors demonstrated papillary architecture and tumor cells with eosinophilic cytoplasm. One case primarily showed sieve-cystic architecture with admixed acinar, solid, and micropapillary structures. Additional histologic findings included papillary adenoma and hemorrhage in some specimens. Notably, oxalate crystals were identified in all ACKD-RCC cases. The majority of tumors also displayed coagulative necrosis and calcification.
Immunohistochemistry showed consistent expression patterns across the cases examined. P504S (AMACR) and CK7 were diffusely or focally positive in all tumors. CA IX staining was negative across cases. CD10 showed small-focal positivity. These staining results contributed to the pathological characterization of the ACKD-related tumors in this cohort.
Nuclear grading using the World Health Organization/International Society of Urological Pathology (WHO/ISUP) system yielded grades of 2–3 for ACKD-RCC cases and 3–4 for the case with pRCC that showed focal sarcomatoid-like differentiation. Pathological staging was pT1 in five RCC patients and pT3a in two patients.
Targeted next-generation sequencing (NGS) and microsatellite instability assessment were performed to identify gene variations related to RCC and markers associated with targeted therapies. NGS detected a PIK3CA point mutation in one ACKD-RCC patient and a SETD2 deletion in the pRCC patient. Both of these patients had marked coagulative necrosis and were staged as pT3a. The authors categorized these two variants as Tier II. No other specific gene alterations or MSI results were detailed in the abstract.
The seven patients with RCC were followed postoperatively for periods ranging from 1 to 32 months. During the follow-up interval, none of the patients received additional adjuvant therapy, and no recurrences or metastases were observed within the reported follow-up window.
From this case series the authors emphasize that ACKD is a frequent complication in dialysis-treated ESRD and that ACKD-associated tumors in this cohort were predominantly papillary in architecture and consistently contained oxalate crystals. The consistent positivity for P504S and CK7, together with negative CA IX staining, were useful pathological features in these cases.
Molecular findings of PIK3CA and SETD2 variants (Tier II) in two patients were associated with prominent necrosis and advanced pathological stage (pT3a), which the authors suggest may indicate a worse prognosis. Based on these observations, the study recommends strengthened imaging surveillance for RCC in young and middle-aged male ESRD patients with long-term dialysis and advocates thorough sampling of kidney specimens to detect atypical renal cysts that may represent precancerous changes. The authors conclude that prognosis for ACKD-RCC should be determined by integrating clinical, pathological, and molecular genetic data.
Note: The abstract is the sole source used for this summary. Details beyond those reported in the abstract — including full NGS panel results, specific immunostaining protocols, or longer-term outcomes — were not provided in the source document.