Fumarate hydratase-deficient renal cell carcinoma (FH-deficient RCC) is a rare and recently described entity associated with hereditary leiomyomatosis and RCC syndrome. FH-deficient RCC may show variable clinical and pathologic findings, but commonly presents with locally advanced and metastatic disease and carries a poor prognosis. We identified 32 patients with FH-deficient RCC, confirmed by FH immunohistochemistry (IHC) and/or FH mutation analysis, and performed a retrospective review of the clinical and pathologic features. Median age at presentation was 43 years (range, 18 to 69 y), and the M:F ratio was 2.2:1. Median tumor size was 6.5 cm (range, 2.5 to 28 cm), and 71% presented at stage ≥pT3a. After a median follow-up of 16 months (range, 1 to 118 mo) in 26 patients, 19% showed no evidence of disease, 31% were alive with disease, and 50% were dead of disease. The vast majority of cases showed multiple histologic growth patterns, with papillary (52%) being the most common predominant pattern, followed by solid (21%), cribriform/sieve-like (14%), sarcomatoid (3%), tubular (3%), cystic (3%), and low-grade oncocytic (3%). Viral inclusion-like macronucleoli with perinucleolar clearing were present in almost all cases (96%). All cases were evaluated using FH IHC, and 3 cases (9%) showed retained FH expression. Nineteen cases had germline or tumor mutation analysis confirming a FH mutation, with 79% (11/14) of cases showing mutations within coding regions and 21% (3/14) showing mutations within intronic splice-sites. By IHC, 97% (32/33) of cases were negative for CK7, 93% (27/29) were negative for p63, and 52% (15/29) were negative for GATA3. All cases stained were positive for PAX8 and showed retained succinate dehydrogenase B expression. Our overall findings show that FH-deficient RCC is considerably heterogenous in morphology and frequently behaves aggressively. Suspicion for this entity should be raised even in the absence of predominantly papillary architecture and characteristic nucleolar features. We have included cases with uncommonly seen features, including 4 cases with predominantly cribriform/sieve-like architecture as well as one case with pure low-grade oncocytic morphology (9 y of clinical follow-up without evidence of disease). Although FH IHC is a useful tool for identifying cases of FH-deficient RCC, not all cases of FH-deficient RCC show loss of FH staining, and FH mutation analysis should be considered for patients with suspicious clinical or pathologic features, even in cases with retained FH IHC expression.

Mediastinal teratomas are enigmatic; those in children and women are almost invariably benign but in men they may be benign or malignant. There are few data on the chromosome 12p status of mediastinal germ cell tumors (GCT), whereas increased 12p copy number is virtually uniform in malignant testicular GCTs. We therefore studied chromosome 12p copy number in 34 diverse mediastinal GCTs and correlated the results with morphology and follow-up to gain insight into possible pathogenesis. Four prepubertal (below 12 y) children (3 females and 1 male), 7 postpubertal females (14 to 52 y) and 6 postpubertal males (12 to 40 y old) had pure, previously untreated teratomas; 15 were mature and 2 had low-grade immaturity. All lacked 12p copy number increase and cytologic atypia, and most (14/17) showed organoid morphology. On follow-up of 16, 1 died of postoperative complications and the remaining 15 were disease free (1 to 119 mo, mean: 39 mo). Eight postpubertal males (19 to 44 y old) had pure teratomas in postchemotherapy resections; 5/8 showed 12p copy number increase. All 8 had distinct cytologic atypia, with organoid morphology in 3. On follow-up, 6 were disease free after surgical resection (1.5 to 94 mo, mean 38 mo); 1 died of disease at 14.5 months, and 1 was alive with metastases at 176 months. Two postpubertal patients, 1 male (29 y) and 1 female (31 y), had teratoma with secondary somatic-type malignancies, with positive 12p copy number increase in the former but not the latter. The man’s tumor occurred after chemotherapy and was a nonorganoid teratoma with primitive neuroectodermal tumor and malignant glioma; the woman’s was a previously untreated organoid teratoma with an undifferentiated carcinoma component. The man died of disease (16 mo) and the woman was alive with metastases (27 mo). Seven patients had resections for mixed GCTs (4) or pure nonteratomatous tumors, all after chemotherapy; 5/7 had positive 12p copy number increase. The teratoma component of the 2 cases having one showed distinct cytologic atypia and lacked organoid morphology. On follow-up, 1 died of disease (5 mo), 2 were alive with disease (1, 1.5 mo), 3 were disease free (1 to 43 mo; mean: 18 mo), and 1 was alive with unknown status (31 mo). Our results support that mediastinal teratomas likely develop from 2 separate pathways. Those in children, women and some men arise as pure neoplasms from a nontransformed precursor cell and, therefore, lack 12p copy number increase, show no cytologic atypia, often have organoid morphology and are benign. Common 12p copy number increase, uniform atypia, infrequent organoid structures and malignant behavior support that pure teratomas after chemotherapy in postpubertal males derive from a malignantly transformed precursor cell. Interestingly, we identified organoid pancreatic differentiation only in the benign group and neuroglia more commonly in the malignant teratomas.

Somatic-type malignancies (SMs) in patients with testicular germ cell tumors (GCT) are rare and mostly attributed to "transformation" of teratoma, although yolk sac tumor (YST) origin has also been proposed. We studied 124 cases of "SM" of testicular GCT origin from 106 patients to evaluate their morphology, immunohistochemical features (especially the utility of SALL4), and relationship to YST. Primitive neuroectodermal and nephroblastomatous tumors were excluded because of prior studies. Patients ranged in age from 15 to 68 years (mean, 33 y). The tumors ranged from 0.7 to 30 cm (mean, 7.6 cm) and involved the retroperitoneum (64%), abdomen/pelvis (10%), lung (10%), mediastinum (6%), supraclavicular region/neck (4%), testis (4%), and thigh (1%). Most initial diagnoses were sarcomas (n=68) or carcinomas (n=51). On review and immunohistochemical analysis, 7 of 45 adenocarcinomas were reclassified as glandular YSTs (GYST) on the basis of glypican-3 (GPC3) and/or α-fetoprotein positivity and scant/absent reactivity for EMA and CK7. These occasionally (29%) had subnuclear and sometimes supranuclear vacuoles (endometrioid-like), whereas adenocarcinomas were more frequently mucinous (17%) or enteric-type (11%) than endometrioid-like (9%). Both expressed CDX2 frequently (83% and 63%, respectively). MUC protein 2, 4, 5, and 6 expression was more common in adenocarcinomas (7% to 36%) than in GYSTs (0% to 20%) but was infrequent. Both were often positive for SALL4, BerEP4, and MOC31; all were negative for TTF-1. On follow-up (GYST: range, 23 to 169 mo; mean, 81mo; adenocarcinoma: range, 1 to 170 mo; mean, 55 mo), 50% and 33% of patients with GYST and adenocarcinoma, respectively, died of disease. We reclassified 26 of 76 sarcomatoid tumors as sarcomatoid YSTs (SYST) on the basis of positive reactivity for both AE1/3 and GPC3. These tumors often had spindled and epithelioid cells in a fibromyxoid stroma. SYSTs were often (60%) SALL4 positive, whereas sarcomas were all negative. On follow-up (SYST: range, 1 to 259 mo; mean, 62 mo; sarcoma: range, 1 to 327 mo; mean, 70 mo), 50% and 29% of patients with SYST and sarcoma, respectively, died of disease, with most mortality occurring in those with high-grade tumors. We conclude that, on the basis of a panel of immunoreactivities, a significant number of "SMs" in testicular GCT patients are more accurately classified as either GYSTs or SYSTs. Ambiguous glandular tumors should be evaluated for GPC3, α-fetoprotein, CK7, and EMA reactivity and sarcomatoid ones for GPC3, AE1/3, and SALL4 reactivity.

Yolk sac tumors may exhibit numerous patterns. One that has received little attention overall, yet is not uncommon, is a solid pattern, which is especially prone to misinterpretation, usually as seminoma, in biopsy specimens from metastatic or mediastinal sites. This distinction is of critical importance as the 2 tumors are treated differently. To determine features useful in the diagnosis of solid yolk sac tumor we reviewed 52 germ cell tumors (28 testicular primaries, 21 metastases from the testis, and 3 mediastinal primaries) that had a yolk sac tumor component with foci of solid growth, defined as a sheet-like arrangement of tumor cells occupying >2 mm and with no or only rare microcysts. Solid yolk sac tumor was almost always associated with other patterns, most commonly microcystic/reticular (75%), glandular (35%), and myxoid (25%). The solid foci consisted of sheets of cells with usually abundant cytoplasm that was mostly (85%) pale to clear and frequently had intercellular basement membrane deposits (75%), rare microcysts (67%), significant nuclear pleomorphism (65%), and hyaline globules (65%). In 2 cases (4%), the cells were small with scant cytoplasm (blastema-like variant). A myxoid background (39%), lymphocytic infiltrate (17%), and an appliqué pattern (8%) were sometimes observed. On immunostaining, AE1/AE3 cytokeratin and glypican 3 provided the most intense and diffuse reactivity for solid yolk sac tumor, whereas α-fetoprotein was negative in 38%. CD117 stained 59%, whereas only rare cells in 1 case (3%) were weakly reactive for podoplanin; OCT3/4 was uniformly negative. We conclude that solid yolk sac tumor can generally be recognized by careful morphologic evaluation, especially its association with other yolk sac tumor patterns, the presence of intercellular band-like deposits of basement membrane, occasional microcysts, nuclear pleomorphism, intracellular hyaline globules, and usual absence of lymphocytes. In difficult cases a concise immunohistochemical panel consisting of AE1/AE3, glypican 3, and OCT3/4 distinguishes solid yolk sac tumor from other neoplasms. α-fetoprotein stains are commonly negative or weak and focal in solid yolk sac tumor and cannot be solely relied on for diagnosis. Common CD117 positivity in solid pattern yolk sac tumors makes it an unreliable discriminator between yolk sac tumor and seminoma.

Accurate diagnosis of plasmacytoid urothelial carcinoma (PUC) is important given its poor prognosis and frequent presentation at high stage. We aim to assess the clinicopathologic features, molecular aberrations, and follow-up data in a series of PUC cases from a single tertiary cancer center. Seventy-two urinary bladder, ureteral, and renal pelvic specimens with urothelial carcinoma with plasmacytoid differentiation were identified. Immunohistochemical (IHC) stains were performed on 48 cases. Among urinary bladder origin markers, GATA3 was most sensitive (96%). Breast carcinoma markers (ER, mammaglobin) were usually negative, but PR stained 1 case (4%). Neuroendocrine markers CD56 and TTF-1 were each positive in 1 case (4% and 4%, respectively). Gastrointestinal adenocarcinoma marker CDX2 was positive in 4 cases (15%), but nuclear β-catenin was negative in all cases. CD138 was positive in 83% and e-cadherin expression was lost in 57% of cases. Fluorescence in situ hybridization (FISH) using the UroVysion Bladder Cancer Kit and FGFR3 mutational analysis using polymerase chain reaction (PCR) were performed on 15 cases; deletion of chromosome 9p21 was common (60%) and FGFR3 mutations were detected in 60% of cases (5 cases had both deletion 9p21 and FGFR3 mutations). Cases were divided into 3 morphologic groups: classic (29%), desmoplastic (35%), and pleomorphic (36%). The three morphologic subtypes had distinct survival outcomes (p=0.083), with median survival for all patients 18 being months versus 10 months for the desmoplastic group.

Clear cell renal cell carcinoma (ccRCC) is the most common and lethal subtype of kidney cancer. Intraoperative frozen section (IFS) analysis is used to confirm the diagnosis during partial nephrectomy. However, surgical margin evaluation using IFS analysis is time consuming and unreliable, leading to relatively low utilization. In our study, we demonstrated the use of desorption electrospray ionization mass spectrometry imaging (DESI-MSI) as a molecular diagnostic and prognostic tool for ccRCC. DESI-MSI was conducted on fresh-frozen 23 normal tumor paired nephrectomy specimens of ccRCC. An independent validation cohort of 17 normal tumor pairs was analyzed. DESI-MSI provides two-dimensional molecular images of tissues with mass spectra representing small metabolites, fatty acids and lipids. These tissues were subjected to histopathologic evaluation. A set of metabolites that distinguish ccRCC from normal kidney were identified by performing least absolute shrinkage and selection operator (Lasso) and log-ratio Lasso analysis. Lasso analysis with leave-one-patient-out crossvalidation selected 57 peaks from over 27,000 metabolic features across 37,608 pixels obtained using DESI-MSI of ccRCC and normal tissues. Baseline Lasso of metabolites predicted the class of each tissue to be normal or cancerous tissue with an accuracy of 94 and 76%, respectively. Combining the baseline Lasso with the ratio of glucose to arachidonic acid could potentially reduce scan time and improve accuracy to identify normal (82%) and ccRCC (88%) tissue. DESI-MSI allows rapid detection of metabolites associated with normal and ccRCC with high accuracy. As this technology advances, it could be used for rapid intraoperative assessment of surgical margin status.K.V.L. and V.S. contributed equally to this work Ryan M. Bain's current address is: Dow Chemical Co., Midland, MI 48674 Additional Supporting Information may be found in the online version of this article.

The risk of gonadal germ cell cancer (GGCC) is increased in selective subgroups, amongst others, defined patients with disorders of sex development (DSD). The increased risk is due to the presence of part of the Y chromosome, i.e., GonadoBlastoma on Y chromosome GBY region, as well as anatomical localization and degree of testicularization and maturation of the gonad. The latter specifically relates to the germ cells present being at risk when blocked in an embryonic stage of development. GGCC originates from either germ cell neoplasia in situ (testicular environment) or gonadoblastoma (ovarian-like environment). These precursors are characterized by presence of the markers OCT3/4 (POU5F1), SOX17, NANOG, as well as TSPY, and cKIT and its ligand KITLG. One of the aims is to stratify individuals with an increased risk based on other parameters than histological investigation of a gonadal biopsy. These might include evaluation of defined susceptibility alleles, as identified by Genome Wide Association Studies, and detailed evaluation of the molecular mechanism underlying the DSD in the individual patient, combined with DNA, mRNA, and microRNA profiling of liquid biopsies. This review will discuss the current opportunities as well as limitations of available knowledge in the context of predicting the risk of GGCC in individual patients.

All authors have no conflict of interest to declare. Abstract 2The clinical and pathologic features of 70 juvenile granulosa cell tumors of the testis are presented. The patients were from 30-weeks gestational age to 10 years old; 60 of 67 (90%) whose age is known to us were < 6 months old. Sixty-two underwent gonadectomy, 6 wedge excision, and 2 only biopsy. Twenty-six tumors were left-sided, and 22 right-sided. Six occurred in an undescended testis and 2 in dysgenetic gonads. The most common presentation was a testicular mass (65%) followed by an "enlarging testis" (25%). Six of 14 patients in whom it was measured had "elevated" serum AFP, likely physiologically, and 1 had gynecomastia. The tumors measured 0.5 to 5 cm (mean, 1.7; median, 1.5) and were most commonly wellcircumscribed and typically yellow-tan; approximately 2/3 had a cystic component, while 1/3 were entirely solid. Microscopic examination typically showed a lobular growth, punctuated in 67 cases by variably-sized and shaped follicles containing material that was basophilic (21%), eosinophilic (44%), or of both characters (35%); 3 lacked follicles. In non-follicular areas, the tumor cells typically grew diffusely, but occasionally had a corded arrangement (26%) or reticular appearance (29%). The stroma was either fibrous or fibromyxoid; hemorrhage associated with hemosiderin-laiden macrophages was focally seen in 16%. The tumor cells were mostly small to medium sized with round to oval nuclei containing inconspicuous nucleoli and moderate to abundant, but occasionally scant, pale to lightly eosinophilic, sometimes vacuolated, cytoplasm; nuclear grooves were infrequent (6%). Focal columnar morphology was seen in 27% of the tumors. Mitoses were plentiful in 37% and apoptosis was prominent in 46%. Intratubular tumor was seen in 43% and entrapped seminiferous tubules in 70%. Lymphovascular invasion was present in 2 cases, rete testis involvement in 4, and necrosis in 1. Rare features/patterns included: regressed tumor with hyalinization and prominent blood vessels (13%), papillary (4%), basaloid (1%), spindle cell predominant (1%), microcystic (1%), adult granulosa cell-like (1%) 3 patterns, and hyaline globules (1%). Inhibin (16/18), calretinin (8/9), WT1 (6/7), FOXL2 (12/12), SF-1 (12/12), and SOX9 (6/11) were positive, while SALL4 and glypican-3 were consistently negative in the neoplastic granulosa cells. Only one tumor was focally positive for AFP. Juvenile granulosa cell tumor is a rare neoplasm with a wide morphologic spectrum that also occurs rarely in undescended testes and dysgenetic gonads. The solid and reticular patterns may pose diagnostic challenges but the lobular appearance and follicular differentiation are characteristic. Immunohistochemical stains may aid in its distinction from other tumors of young males, particularly yolk sac tumor, a neoplasm that peaks at a somewhat later age. Twenty-four patients with follow-up, including 4 of 6 patients treated with wedge resection /biopsy, had no evidence of disease (2-348 months; mean, 83...