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When multiple cores are biopsied from a single magnetic resonance imaging (MRI)-targeted lesion, Gleason grade may be assigned for each core separately or for all cores of the lesion in aggregate. Because of the potential for disparate grades, an optimal method for pathology reporting MRI lesion grade awaits validation. We examined our institutional experience on the concordance of biopsy grade with subsequent radical prostatectomy (RP) grade of targeted lesions when grade is determined on individual versus aggregate core basis. For 317 patients (with 367 lesions) who underwent MRI-targeted biopsy followed by RP, targeted lesion grade was assigned as (1) global Grade Group (GG), aggregated positive cores; (2) highest GG (highest grade in single biopsy core); and (3) largest volume GG (grade in the core with longest cancer linear length). The 3 biopsy grades were compared (equivalence, upgrade, or downgrade) with the final grade of the lesion in the RP, using κ and weighted κ coefficients. The biopsy global, highest, and largest GGs were the same as the final RP GG in 73%, 68%, 62% cases, respectively (weighted κ: 0.77, 0.79, and 0.71). For cases where the targeted lesion biopsy grade scores differed from each other when assigned by global, highest, and largest GG, the concordance with the targeted lesion RP GG was 69%, 52%, 31% for biopsy global, highest, and largest GGs tumors (weighted κ: 0.65, 0.68, 0.59). Overall, global, highest, and largest GG of the targeted biopsy show substantial agreement with RP-targeted lesion GG, however targeted global GG yields slightly better agreement than either targeted highest or largest GG. This becomes more apparent in nearly one third of cases when each of the 3 targeted lesion level biopsy scores differ. These results support the use of global (aggregate) GG for reporting of MRI lesion-targeted biopsies, while further validations are awaited.

Renal transplant recipients are at increased risk of developing urologic malignancies, some of which are associated with prolonged BK virus infection. We report two cases of BK virus-associated carcinoma with variant morphological patterns (clear cell adenocarcinoma of the bladder and micropapillary urothelial carcinoma of the pelvicaliceal system) arising in the urinary tract of renal transplant recipients. In both cases, the diagnosis was initially established on cytologic specimens: on urine cytology in one patient and on fine needle aspiration of an inguinal lymph node in the other patient. The unusual cytologic features of both cases (multiple morphologies in one patient and micropapillary pattern in the other), co-occurrence of decoy cells in the urine of one patient and the occurrence of these tumors in renal transplant recipients raised the possibility of BK polyomavirus-associated malignancy and led to confirmatory SV40 immunostains that were positive. These cases expand the morphologic variants of BK virus-associated urologic malignancies diagnosed in solid organ transplant patients. While differentiating BK virus-infected cells from malignant cells in urine cytology specimens is a diagnostic challenge, greater awareness of their possible co-existence is vital, as this could be the only chance for an early diagnosis.