Anatomic pathology selected abstracts

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Diagnostic challenge of urine cytology findings in pseudocarcinomatous urothelial hyperplasia of bladder

Pseudocarcinomatous urothelial hyperplasia mimics cancer architecturally and cytologically. Its urine cytology features have not been described previously. Therefore, the authors conducted a study to describe pseudocarcinomatous urothelial hyperplasia (PCUH) features in urine cytology. They reviewed urine cytology cases with concurrent PCUH tissue specimens from five academic institutions and classified them using Paris System criteria. The review included 39 patients (31 men and eight women) who were a mean age of 67 years (range, 39–87 years). All patients had prior pelvic irradiation and most presented with hematuria (n = 27). The specimens included voided urine (n=16); bladder washing (n=11); and urine, not otherwise specified (n=12). Specimen preparation included the use of cytospin (n = 29) and Hologic ThinPrep (n = 10). Original interpretations were negative for high-grade urothelial carcinoma (n = 28), atypical urothelial cells (n = 10), and high-grade urothelial carcinoma (HGUC; n = 1). Twenty-five (64 percent) urine specimens had findings of PCUH. These specimens were moderately cellular and comprised of sheets, cohesive groups, or isolated urothelial cells. Nucleoli were present in 23 cases. The nuclear membrane was smooth to irregular (n = 9), smooth (n = 8), or irregular (n = 8). The chromatin was glassy (n = 8), vesicular (n = 7), hyperchromatic (n = 7), or vesicular to finely granular (n = 3). The cytoplasm varied from dense squamoid, to finely vacuolated, to vacuolated. Nucleomegaly was observed in all 25 specimens, and nucleo-cytoplasmic ratio greater than 0.5 was seen in 11 of 25 (44 percent) cases. The background contained acute inflammation (n = 14), was clean (n = 9), or contained red blood cells (n = 2). All cases originally interpreted as atypical urothelial cells and HGUC had features of PCUH. PCUH urine features can overlap those of atypical urothelial cells, HGUC, and nonurothelial malignancies. In the study cohort, 44 percent (11 of 25) of urine specimens with PCUH changes were initially misclassified. The authors concluded that it is important to recognize cytologic features of PCUH to avoid overcalling reactive changes.

Velez Torres JM, Gonzalez ML, Duarte EM, et al. Urine cytology findings in cases of pseudocarcinomatous urothelial hyperplasia of the bladder often represent a diagnostic challenge. Arch Pathol Lab Med. 2023;147:716–721.

Correspondence: Dr. Oleksandr N. Kryvenko at o.kryvenko@med.miami.edu

Encapsulated papillary carcinoma of breast: Does it have a native basement membrane?

Encapsulated papillary carcinoma is surrounded by a thick fibrous capsule-like structure, which is considered a thickened basement membrane. The authors conducted a study to describe the geometric characteristics of the encapsulated papillary carcinoma (EPC) capsule and determine whether it is an expansion of the basement membrane or a stromal reactive process. For the study, 100 cases of normal and neoplastic breast tissue were divided into four groups of 25 each. The groups included EPC, as well as ductal carcinoma in situ (DCIS), normal breast tissue, and invasive carcinoma as control groups. Representative slides from each case were stained with picrosirius red and examined using polarized microscopy. Images were analyzed using the ImageJ, CT-FIRE, and Curve Align image-analysis programs. Compared with the normal and DCIS basement membrane, the EPC capsule showed a significant increase in collagen fiber width, straightness, and density, and a decrease in fiber length. The fibers in the EPC capsule were less aligned and had a more perpendicular arrangement. Furthermore, the EPC capsule was enriched with disorganized collagen type one (stromal collagen) fibers. Compared with the other groups, the EPC capsule showed significant variation in the thickness, evenness, and distribution of collagen fibers, as well as significant intracapsular heterogeneity. Compared with the basement membrane-like material in the invasive group, the EPC capsule had a higher density of collagen fiber with longer, straighter, and more aligned fibers but no difference in the distribution of collagen types one and three. No differences were found between EPC and encapsulated papillary thyroid carcinoma (EPTC) capsules, except that the fibers in the EPC capsule were straighter. Although differences in collagen fiber density, straightness, orientation, and alignment were detected between normal ducts and lobules and DCIS basement membrane, both were significantly different from the EPC capsule. This study provided evidence that the EPC capsule is a reactive process rather than a thickened native basement membrane characteristic of normal and in situ lesions. It provides further evidence that EPC is an indolent invasive carcinoma based on capsule characteristics.

Ghannam SF, Rutland CS, Allegrucci C, et al. Encapsulated papillary carcinoma of the breast: does it have a native basement membrane? Histopathology. 2023;83(3):376–393.

Correspondence: Dr. Emad Rakha at mrzear1@exmail.nottingham.ac.uk