Vascular tumors of the kidney are distinctly rare, and to date no large series have been reported. We analyzed a series of primary vascular tumors of the kidney to further delineate their clinicopathologic features and identify organ-specific morphologic features, if present. Twenty-five renal cases previously coded as "arteriovenous malformation," "hemangioma," and "angiosarcoma" were retrieved from the archives of 4 collaborating institutions and were reevaluated histologically. Tumors were classified according to the 2002 World Health Organization classification of tumors of soft tissue and bone. There were 18 males and 7 females (M:F=2.6:1) ranging from 21 to 95 years (mean 56.7 y). Lesions ranged from "microscopic" to 30 cm (mean 6.0 cm) and were tan-brown, cystic, and hemorrhagic. On re-review, cases were classified as arteriovenous malformation (n=3), capillary hemangioma (n=14), and angiosarcoma (n=8). Arteriovenous malformations were identical to their somatic soft tissue counterparts. Renal capillary hemangiomas often lacked a well-formed lobular pattern and 5 cases showed a "sieve-like" arrangement reminiscent of splenic sinusoids, a pattern previously noted by others (anastomosing hemangioma). All hemangiomas were noninfiltrative and lacked cytologic atypia and mitotic activity. GLUT-1, D2-40, and CD8 were performed in 3 anastomosing hemangiomas and were all negative. Angiosarcomas were diffusely infiltrative with extensive parenchymal destruction; all showed at least small areas of conventional vasoformative growth, but were frequently dominated by spindled and epithelioid histology. All cases were positive for some combination of vascular tumor-associated markers (CD31, CD34, and FLI-1). Cytokeratin expression was absent in all angiosarcomas. Follow-up was available for 15 cases: all patients with arteriovenous malformation and hemangioma with follow-up were disease free after complete excision; 4 cases of angiosarcoma died of the disease at 1, 1, 6, and 11 months. Our review shows that many capillary hemangiomas of the kidney are morphologically distinctive tumors, which often show "spleen-like" or "anastomosing" features. Angiosarcomas of the kidney are highly aggressive tumors with poor outcome and may have morphologic features (spindling and epithelioid change), which could result in confusion with sarcomatoid carcinomas and other renal mesenchymal tumors.
Accurate recognition of muscularis propria invasion by urothelial carcinoma is vital as it serves as a crossroad between conservative and aggressive clinical management. Recently, there has been attention to the hyperplastic pattern of muscularis mucosae which may mimic the muscularis propria. We have earlier shown that smoothelin, a marker of terminally differentiated smooth muscle cells, is relatively specific for muscularis propria (positive staining) and is variably negative to weak in muscularis mucosae. The earlier study was based on cystectomy specimen slides in which the bladder cancer was not present. Pathologic staging in transurethral resection of urinary bladder tumor (TURBT) specimens is complicated by limited, unoriented, or highly cauterized samples. Herein, we test the capability of smoothelin to recognize muscularis propria in TURBT specimens to further substantiate its diagnostic applicability in routine practice. Representative sections from 70 TURBTs were immunostained with smoothelin, and muscularis propria was evaluated in H&E slides and the corresponding smoothelin immunohistochemistry slides using double-blinded analysis. In 31/70 (44%) cases, muscularis propria was involved by invasive carcinoma. Cautery artifact was present in 46/70 (66%) cases, which did not seem to affect smoothelin immunohistochemistry staining of the muscularis propria. Muscularis propria was present by H&E in 48/70 (69%) cases and 48/70 (69%) cases had muscularis propria by smoothelin immunohistochemistry-based 2 (+) or 3 (+) positivity in larger muscle bundles with round regular contours. Desmoplastic response to invasive carcinoma stained negatively for smoothelin. The sensitivity, specificity, positive predictive value, and negative predictive value of smoothelin based on comparison with morphology in TURBT specimens was 98%, 95%, 98%, and 95%, respectively. This study confirms the relatively high sensitivity and specificity for smoothelin in MP, including in TURBT specimens. Immunoreactivity is retained despite the presence of thermal tissue injury, desmoplasia, or involvement by carcinoma. Our data confirm the use of smoothelin in the accurate distinction between muscularis propria and muscularis mucosae or desmoplastic reactions, thereby facilitating appropriate pathologic stage designation in often challenging TURBT specimens.
Thymic carcinoma (primary carcinoma of the thymic epithelium; type C thymoma) is a rare malignancy. It usually presents in middle-aged to elderly patients and can exhibit a wide variety of morphologic appearances. Thymic basaloid carcinoma (thymic BC) is a particularly rare subtype, with less than 20 cases published in the English literature, mostly in the form of individual case reports. In this study, we present the clinicopathologic and immunohistochemical features of 12 new cases of thymic BC. There were 10 (83%) men and 2 (17%) women. Ages at the time of initial diagnosis ranged from 34 to 77 years (mean 55 y). The 2 most common manners of presentation were dyspnea on exertion (3 patients) and as an incidental finding on radiographic imaging (2 patients). Tumors ranged in size from 4.4 to 17 cm (mean 10.1 cm). One of 12 cases (8.3%) was associated with a multilocular thymic cyst. Immunohistochemistry was performed in 8 cases. Pan-cytokeratin was positive in all cases. CD117 (c-kit) was positive in 6 of 8 cases (75%), p63 was positive in 7 of 8 cases (88%), p53 was positive in 7 of 8 cases (88%), ranging from <10% to 90%, CD5 was focally positive in 3 of 8 cases (38%), collagen type IV was positive in 4 of 8 cases (50%), and proliferative index, as estimated by Ki67, ranged from <1% to approximately 15%. In 1 of 2 cases with sarcomatoid differentiation, Ki67 was greater than 80% in the sarcomatoid area. Cases were negative for thyroid transcription factor-1 (0 of 8), S-100 (0 of 7), and synaptophysin (0 of 7). Long-term data was available in 8 patients with an average follow-up of 30 months. Five patients died of their disease at an average of 34 months from the time of diagnosis. Of the remaining 3 patients, 1 had a stable recurrence and died at 4 years from unrelated causes, and 2 were alive without the evidence of disease at 12 and 7 months, respectively. Thymic BC, although previously regarded as a low-grade neoplasm, has shown that it is capable of aggressive behavior and significant mortality. In this paper, we review the pertinent literature and discuss the possible relationship of thymic BC with thymic adenoid cystic carcinoma, as well as BCs and adenoid cystic carcinomas at other sites.
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