Hereditary leiomyomatosis and renal cell carcinoma syndrome-associated renal cell carcinomas (RCC) are difficult to diagnose prospectively. We used immunohistochemistry (IHC) to identify fumarate hydratase (FH)-deficient tumors (defined as FH negative, 2-succinocysteine [2SC] positive) in cases diagnosed as "unclassified RCC, high grade or with papillary pattern," or "papillary RCC type 2," from multiple institutions. A total of 124 tumors (from 118 patients) were evaluated by IHC for FH and 2SC. An FH deficiency was found in 24/124 (19%) cases. An indeterminate result (only 1 marker abnormal) was found in 27/124 (22%) cases. In a tissue microarray of 776 RCCs of different types, only 2 (0.5%) tumors, initially considered papillary type 2, were FH deficient. FH mutations were found in 19/21 FH-deficient tumors (with confirmed germline mutations in 9 of 9 tumors in which germline status could be assessed) and in 1/26 FH-indeterminate tumors identified by IHC. No FH mutations were found in 2/21 FH-deficient RCCs, 25/26 FH-indeterminate RCCs, and 10/10 RCCs demonstrating FH expression by IHC. Patients with FH-deficient RCC had a median age of 44 years (range, 21 to 65 y). Average tumor size was 8.2 cm (range, 0.9 to 18 cm). FH-deficient RCCs were characterized by at least focal macronucleoli and demonstrated 2 or more growth patterns in 93% cases. Papillary was the most common (74%) and dominant (59%) pattern, whereas other common patterns included: solid (44%), tubulocystic (41%), cribriform (41%), and cystic (33%). At presentation, 57% were stage ≥pT3, 52% had positive nodes, and 19% had distant metastases. After a mean follow-up of 27 months (range, 1 to 114 mo), 39% of patients were dead of disease, and 26% had disease progression. We conclude that FH and 2SC are useful IHC ancillary tools, which allow recognition of FH-deficient RCC.

The Internet has become an important health information resource for patients and the general public. Wikipedia, a collaboratively written Web-based encyclopedia, has become the dominant online reference work. It is usually among the top results of search engine queries, including when medical information is sought. Since April 2004, editors have formed a group called WikiProject Medicine to coordinate and discuss the English-language Wikipedia’s medical content. This paper, written by members of the WikiProject Medicine, discusses the intricacies, strengths, and weaknesses of Wikipedia as a source of health information and compares it with other medical wikis. Medical professionals, their societies, patient groups, and institutions can help improve Wikipedia’s health-related entries. Several examples of partnerships already show that there is enthusiasm to strengthen Wikipedia’s biomedical content. Given its unique global reach, we believe its possibilities for use as a tool for worldwide health promotion are underestimated. We invite the medical community to join in editing Wikipedia, with the goal of providing people with free access to reliable, understandable, and up-to-date health information.

The spectrum of the renal oncocytic tumors has been expanded in recent years to include several novel and emerging entities. We describe a cohort of novel, hitherto unrecognized and morphologically distinct high-grade oncocytic tumors (HOT), currently diagnosed as "unclassified" in the WHO classification. We identified 14 HOT by searching multiple institutional archives. Morphologic, immunohistochemical (IHC), molecular genetic, and molecular karyotyping studies were performed to investigate these tumors. The patients included 3 men and 11 women, with age range from 25 to 73 years (median 50, mean 49 years). Tumor size ranged from 1.5 to 7.0 cm in the greatest dimension (median 3, mean 3.4 cm). The tumors were all pT1 stage. Microscopically, they showed nested to solid growth, and focal tubulocystic architecture. The neoplastic cells were uniform with voluminous oncocytic cytoplasm. Prominent intracytoplasmic vacuoles were frequently seen, but no irregular (raisinoid) nuclei or perinuclear halos were present. All tumors demonstrated prominent nucleoli (WHO/ISUP grade 3 equivalent). Nine of 14 cases were positive for CD117 and cytokeratin (CK) 7 was either negative or only focally positive in of 6/14 cases. All tumors were positive for AE1-AE3, CK18, PAX 8, antimitochondrial antigen, and SDHB. Cathepsin K was positive in 13/14 cases and CD10 was positive in 12/13 cases. All cases were negative for TFE3, HMB45, Melan-A. No TFEB and TFE3 genes rearrangement was found in analyzable cases. By array CGH, complete chromosomal losses or gains were not found in any of the cases, and 3/9 cases showed absence of any abnormalities. Chromosomal losses were detected on chromosome 19 (4/9), 3 with losses of the short arm (p) and 1 with losses of both arms (p and q). Loss of chromosome 1 was found in 3/9 cases; gain of 5q was found in 1/9 cases. On molecular karyotyping, 3/3 evaluated cases showed loss of heterozygosity (LOH) on 16p11.2-11.1 and 2/3 cases showed LOH at 7q31.31. Copy number (CN) losses were found at 7q11.21 (3/3), Xp11.21 (3/3), Xp11.22-11.21 (3/3), and Xq24-25 (2/3). CN gains were found at 13q34 (2/3). Ten patients with available follow up information were alive and without disease progression, after a mean follow-up of 28 months (1 to 112 months). HOT is a tumor with unique morphology and its IHC profile appears mostly consistent. HOT should be considered as an emerging renal entity because it does not meet the diagnostic criteria for other recognized eosinophilic renal tumors, such as oncocytoma, chromophobe renal cell carcinoma (RCC), TFE3 and TFEB RCC, SDH-deficient RCC, and eosinophilic solid and cystic RCC.

A unique renal neoplasm characterized by eosinophilic cytoplasm and solid and cystic growth was recently reported in patients with tuberous sclerosis complex (TSC). We searched multiple institutional archives and consult files in an attempt to identify a sporadic counterpart. We identified 16 morphologically identical cases, all in women, without clinical features of TSC. The median age was 57 years (range, 31 to 75 y). Macroscopically, tumors were tan and had a solid and macrocystic (12) or only solid appearance (4). Average tumor size was 50 mm (median, 38.5 mm; range, 15 to 135 mm). Microscopically, the tumors showed solid areas admixed with variably sized macrocysts and microcysts that were lined by cells with a pronounced hobnail arrangement. The cells had voluminous eosinophilic cytoplasm with prominent granular cytoplasmic stippling and round to oval nuclei with prominent nucleoli. Scattered histiocytes and lymphocytes were invariably present. Thirteen of 16 patients were stage pT1; 2 were pT2, and 1 was pT3a. The cells demonstrated a distinct immunoprofile: nuclear PAX8 expression, predominant CK20-positive/CK7-negative phenotype, patchy AMACR staining, but no CD117 reactivity. Thirteen of 14 patients with follow-up were alive and without disease progression after 2 to 138 months (mean: 53 mo; median: 37.5 mo); 1 patient died of other causes. Although similar to a subset of renal cell carcinomas (RCCs) seen in TSC, we propose that sporadic "eosinophilic, solid, and cystic RCC," which occurs predominantly in female individuals and is characterized by distinct morphologic features, predominant CK20-positive/CK7-negative immunophenotype, and indolent behavior, represents a novel subtype of RCC.