CIC-DUX4 gene fusion, resulting from either a t(4;19) or t(10;19) translocation, is the most common genetic abnormality detected in EWSR1-negative small blue round cell tumors. Following their discovery it was debated if these tumors should be classified as variants of Ewing sarcoma (ie, atypical Ewing sarcoma) or as a stand-alone pathologic entity. As such the WHO classification temporarily grouped the CIC-rearranged tumors under undifferentiated sarcomas with round cell phenotype, until further clinical evidence was available. However, most studies reported so far include small series with limited follow-up information, which preclude a more definitive assessment. The present work investigates the clinicopathologic features of a large cohort of sarcomas with CIC gene rearrangement, to define their clinical presentation, morphologic spectrum, and outcome. Our study further examines the overall survival of the CIC-positive cohort compared with a control group of EWSR1-rearranged Ewing sarcoma matched for age and stage. The study cohort included 115 patients, with a mean age of 32 years and a slight male predominance. Most tumors occurred in the soft tissue (86%), predominantly deep-seated and equally divided among trunk and extremity, followed by visceral locations (12%) and rarely in the bone (3%). Microscopically, most tumors showed round to ovoid cytomorphology but half of the cases showed also focal areas of spindling and epithelioid/rhabdoid phenotype, with frequent myxoid stromal changes. Variable CD99 reactivity was seen in 84% cases, with a diffuse pattern only in 23% of cases, whereas nuclear WT1 was seen in 92%. A CIC-DUX4 fusion was detected in 57% of cases, with either DUX4 on 4q35 (35%) or on 10q26 in 25 (22%) cases. No FOXO4 gene rearrangements were present in 39 cases tested. Clinical follow-up was available in 57 patients, with a 5-year survival of 43%, which was significantly lower than the 77% 5-year survival in the control Ewing sarcoma group (P=0.002). Our findings show that CIC-DUX4 sarcomas occur most commonly in young adults within the somatic soft tissues, having a wide spectrum of morphology including round, epithelioid and spindle cells, and associated with an aggressive clinical course, with an inferior overall survival compared with Ewing sarcoma. The results support the classification of CIC-rearranged tumors as an independent molecular and clinical subset of small blue round cell tumors distinct from Ewing sarcoma.

The current epidemiology and clinicopathologic features of squamous cell carcinoma (SCC) of the scrotum are largely unknown because of its low incidence. We describe the histopathologic features, immunohistochemistry, and human papillomavirus (HPV) status of 29 patients with scrotal SCC. The mean age at presentation was 55 years (range, 30 to 74 y). White to black ratio was 1.9:1. There was no predominant occupation, with the majority being white-collar professionals. Clinical history of condylomas was present in 5 patients, and 7 patients had a history of multiple skin cancers including melanoma, basal cell carcinoma, and other SCCs. Other comorbidities included human immunodeficiency virus infection (n=2), kidney transplant (n=1), leukemia/lymphoma (n=2), hidradenitis suppurativa (n=1), chronic scrotal infections with abscess (n=1), inflamed epidermal inclusion cyst (n=1), and lichen planus (n=1). One patient had a history of regular tanning bed use. Morphologically, the majority was usual type (n=17), followed by basaloid (n=7) and warty (n=5). Nineteen cases were in situ, and 10 were invasive. Three patients had inguinal lymphadenopathy; in 1, metastasis was confirmed. Suprabasal nuclear staining for Ki67 was considered positive. For p16, a continuous band of nuclear and cytoplasmic staining was considered positive, and a noncontinuous or absence of staining was considered negative. p16 was positive in 10 cases; high-risk HPV was confirmed in 7 cases. Ki67 was positive in 8/17 (47%) usual, 6/7 (85.7%) basaloid, and 3/5 (60%) warty type. p53 was positive in 5/17 (29.4%) usual, 2/7 (28.6%) basaloid, and 1/5 (20%) warty type. All patients were treated with local excision only; 13 had positive margins. Three patients were treated with imiquimod after local excision. The median follow-up was 30 months. Three patients recurred and were treated with re-excision; 1 patient received radiotherapy. Overall, the morphologic, immunohistochemical, and HPV studies show that, similar to SCC of the vulva or penis, the SCC of the scrotum can be divided into 2 major groups. Group 1 (38.5%): positive for p16 and elevated Ki67. This group is associated with HPV infection and displays predominantly a basaloid or warty morphology, although a number of them are of usual type. Group 2 (61.5%): negative for p16. This group has variable Ki67 expression, is consistently negative for HPV, and displays predominantly usual-type morphology. SCC of the scrotum in the United States currently affects primarily white-collar professionals. The majority present with in situ lesions, and the high rate of positive margins at first excision suggests that they are clinically ill-defined lesions. No longer are occupational exposures to carcinogens the major etiology of scrotal SCC. Rather in contemporary times, common risk factors include HPV infection, immunocompromised states, and chronic scrotal inflammatory conditions.

The source and roles of fibroblasts and T-cells during maladaptive remodeling and myocardial fibrosis in the setting of pulmonary arterial hypertension (PAH) have been long debated. We demonstrate, using single-cell mass cytometry, a subpopulation of endogenous human cardiac fibroblasts expressing increased levels of CD4, a helper T-cell marker, in addition to myofibroblast markers distributed in human fibrotic RV tissue, interstitial and perivascular lesions in SUGEN/Hypoxia (SuHx) rats, and fibroblasts labeled with pdgfrα CreERt2/+ in R26R-tdTomato mice. Recombinant IL-1β increases IL-1R, CCR2 receptor expression, modifies the secretome, and differentiates cardiac fibroblasts to form CD68-positive cell clusters. IL-1β also activates stemness markers, such as NANOG and SOX2, and genes involved in dedifferentiation, lymphoid cell function and metabolic reprogramming. IL-1β induction of lineage traced primary mouse cardiac fibroblasts causes these cells to lose their fibroblast identity and acquire an immune phenotype. Our results identify IL-1β induced immune-competency in human cardiac fibroblasts and suggest that fibroblast secretome modulation may constitute a therapeutic approach to PAH and other diseases typified by inflammation and fibrotic remodeling.