Categorizing renal oncocytic neoplasms on core needle biopsy: a morphologic and immunophenotypic study of 144 cases with clinical follow-up.

There is limited literature on renal oncocytic neoplasms diagnosed on core biopsy. All renal oncocytic neoplasm core biopsies from 2006 to 2013 were retrospectively reviewed. Morphologic features and an immunohistochemical panel of CK7, c-KIT, and S100A1 were assessed. Concordance with resection diagnosis, statistical analysis including a random forest classification, and follow-up were recorded. The post-immunohistochemical diagnoses of 144 renal oncocytic core biopsies were favor oncocytoma (67%), favor renal cell carcinoma (RCC) (12%), and cannot exclude RCC (21%). Diagnosis was revised following immunohistochemistry in 7% of cases. The most common features for oncocytoma (excluding dense granular cytoplasm) were nested architecture, edematous stroma, binucleation and tubular architecture; the most common features for favor RCC were sheet-like architecture, nuclear pleomorphism, papillary architecture, and prominent cell borders. High nuclear grade, necrosis, extensive papillary architecture, raisinoid nuclei, and frequent mitoses were not seen in oncocytomas. Comparing the pathologist and random forest classification, the overall out-of-bag estimate of classification error dropped from 23% to 13% when favor RCC and cannot exclude RCC were combined into 1 category. Resection was performed in 19% (28 cases) with a 94% concordance (100% of favor RCC biopsies and 90% of cannot exclude RCC biopsies confirmed as RCC; 83% of favor oncocytomas confirmed); ablation in 23%; and surveillance in 46%. Follow-up was available in 92% (median follow-up, 33months) with no adverse outcomes. Renal oncocytic neoplasms comprise a significant subset (16%) of all core biopsies, and the majority (78%) can be classified as favor oncocytoma or favor RCC.

Evaluation of PAX2 and PAX8 expression in salivary gland neoplasms.

PAX2 and PAX8 are transcription factors involved in embryogenesis that have been utilized as immunohistochemical indicators of tumor origin. Specifically, PAX2 is a marker of neoplasms of renal and müllerian origin, while PAX8 is expressed by renal, müllerian, and thyroid tumors. While studies examining these transcription factors in a variety of tumors have been published, data regarding their expression in salivary gland neoplasms are limited. The goal of this study was to assess expression of PAX2 and PAX8 in a large cohort of salivary gland tumors. Utilizing tissue microarrays, samples of normal salivary glands (n = 68) and benign and malignant salivary gland neoplasms (n = 442) were evaluated for nuclear immunoreactivity with PAX2 and PAX8. No expression was observed with either marker in the normal salivary glands, and PAX8 was negative in all neoplasms. Focal expression of PAX2 was observed in one example each of oncocytoma and acinic cell carcinoma. These results indicate that evaluation of PAX2 and/or PAX8 expression would be valuable in differentiating primary salivary gland tumors from metastases known to express PAX2 and/or PAX8.

Inflammatory myofibroblastic tumor of the bladder.

We illustrate a case of an inflammatory myofibroblastic tumor (IMT) involving the bladder in a woman with dysuria and review the literature and differential diagnosis. Inflammatory myofibroblastic tumor, also referred to as pseudosarcomatous myofibroblastic proliferation, is a rare lesion that can arise in the genitourinary system and is characterized by a fascicular arrangement of myofibroblasts with admixed inflammatory cells and slitlike vessels. Urinary bladder IMT can be a diagnostic pitfall because its histologic features (brisk mitoses, invasion into muscularis propria, and prominent nucleoli) can mimic malignancy. The differential diagnosis of urinary bladder IMT includes sarcomatoid carcinoma and leiomyosarcoma. Diagnostic features such as bland nuclear chromatin, ganglion-like cells, pale eosinophilic cytoplasm with long processes, overexpression of anaplastic lymphoma kinase (immunohistochemistry or gene rearrangement studies), and the absence of atypical mitoses help distinguish IMT from its malignant mimics. Current controversies regarding postoperative spindle cell nodule and IMT are discussed.

Diagnostic evaluation of metastatic rhabdomyosarcoma in effusion specimens.

Sarcomas, including rhabdomyosarcoma (RMS), are rarely encountered in effusion specimens; therefore, difficulties in the accurate diagnosis of metastatic sarcomas in effusions can occasionally arise. Immunohistochemistry for myogenin has emerged as a useful adjunct in the diagnosis of RMS, especially in small biopsy specimens. To date, there are no published series describing the utility of immunocytochemistry for myogenin in the diagnosis of RMS in effusion specimens. A total of 15 patients, for whom metastatic sarcomas were diagnosed in effusion specimens between 1998 and 2012, were identified for analysis: alveolar RMS (n = 5); embryonal RMS (n = 1); pleomorphic RMS (n = 1); angiosarcoma (n = 1); Ewing's sarcoma (n = 2); osteosarcoma (n = 1); endometrial stromal sarcoma (n = 1); unclassified spindle cell sarcoma (n = 1); unclassified/undifferentiated pleomorphic sarcoma (n = 1); and leiomyosarcoma (n = 1). Immunocytochemistry for myogenin was performed for each of these cases as well as for 102 effusions that were positive for metastatic carcinoma. Immunocytochemistry for myogenin diffusely and strongly highlighted the nuclei of the tumor cells in six (86%) of seven cases of metastatic RMS; specifically, the five alveolar RMS and one embryonal RMS cases. The one case of pleomorphic RMS, the eight remaining metastatic sarcoma cases, and all 102 cases of metastatic carcinoma were completely negative for myogenin expression. In conclusion, immunocytochemistry for myogenin is a sensitive and specific ancillary adjunct in the diagnostic evaluation of metastatic RMS in effusion specimens.

Accuracy of determining small renal mass management with risk stratified biopsies: confirmation by final pathology.

PURPOSE: We assess the accuracy of a biopsy directed treatment algorithm in correctly assigning active surveillance vs treatment in patients with small renal masses by comparing biopsy results with final surgical pathology. MATERIALS AND METHODS: From 1999 to 2011, 151 patients with small renal masses 4 cm or smaller underwent biopsy and subsequent surgical excision. Biopsy revealed cell type and grade in 133 patients, allowing the hypothetical assignment of surveillance vs treatment using an algorithm incorporating small renal mass size and histological risk group. We compared the biopsy directed management recommendation with the ideal management as defined by final surgical pathology. RESULTS: Biopsy called for surveillance of 36 small renal masses and treatment of 97 small renal masses. Final pathology showed 11 patients initially assigned to surveillance should have been assigned to treatment (8.3% of all patients, 31% of those recommended for surveillance), whereas no patients moved from treatment to surveillance. Agreement between biopsy and final pathology was 92%. Using management based on final pathology as the reference standard, biopsy had a negative predictive value of 0.69 and positive predictive value 1.0 for determining management. Of the 11 misclassified cases, 7 had a biopsy indicating grade 1 clear cell renal cancer which was upgraded to grade 2 (5) or grade 3 (2). After modifying the histological risk group assignment to account for undergrading of clear cell renal cancer, agreement improved to 97%, with a negative predictive value of 0.86 and a positive predictive value of 1.0. CONCLUSIONS: Our results suggest that compared to final pathology, biopsy of small renal masses accurately informs an algorithm incorporating size and histological risk group that directs the management of small renal masses.