PEComas, occasionally associated with the tuberous sclerosis complex, are defined by the presence of perivascular epithelioid cells that coexpress muscle and melanocytic markers. This family of tumors includes angiomyolipoma (AML), clear cell sugar tumor of the lung (CCST), lymphangioleiomyomatosis (LAM), and very rare tumors in other locations. Because non-AML/non-LAM PEComas are extremely rare and their natural history and prognostic features undefined, we present our experience with 26 PEComas of soft tissue and the gynecologic tract, the largest series to date. We also performed a detailed review of the literature, with special attention to features predictive of clinical behavior. All PEComas exclusive of AML and LAM were retrieved from our consultation files. Immunohistochemistry for pan-cytokeratin (CK), S-100 protein, smooth muscle actins (SMA), desmin, vimentin, HMB45, Melan-A, microphthalmia transcription factor (MiTF), TFE3, CD117, and CD34 was performed. Clinical follow-up information was obtained. Fisher's exact test was performed. The median patient age was 46 years (range, 15-97 years); there was a marked female predominance (22 females, 4 males). Sites of involvement included the omentum or mesentery (6 cases), uterus (4 cases), pelvic soft tissues (3 cases), abdominal wall (2 cases), uterine cervix (2 cases), and vagina, retroperitoneum, thigh, falciform ligament, scalp, broad ligament, forearm, shoulder, and neck (1 case each). The tumors ranged from 1.6 to 29 cm in size (median, 7.8 cm). Tumors were epithelioid (N = 9), spindled (N = 7), or mixed (N = 10). Multinucleated giant cells were present in 18 cases. High nuclear grade was noted in 10 cases, high cellularity in 7 cases, necrosis in 8 cases, and vascular invasion in 3 cases. Mitotic activity was 0 to 50 mitotic figures (MF)/50 high power fields (HPF) (median, 0 MF/50 HPF) with atypical MF in 6 cases. IHC results were: SMA (20/25), desmin (8/22), HMB45 (22/24), Melan-A (13/18), MITF (9/18), S-100 protein (8/24), CK (3/23), vimentin (12/14), TFE3 (5/17), c-kit (1/20), and CD34 (0/7). Clinical follow-up (24 of 26 patients, 92%; median, 30 months; range, 10-84 months) showed 3 local recurrences and 5 distant metastases. At last available clinical follow-up, 2 patients (8%) were dead of disease, 4 patients (17%) were alive with metastatic or unresectable local disease, and 18 patients (75%) were alive with no evidence of disease. No patient in our series had a history of tuberous sclerosis complex. Recurrence and/or metastasis was strongly associated tumor size > median size (8 cm), mitotic activity greater than 1/50 HPF, and necrosis. We conclude that PEComas of soft tissue and gynecologic origin may be classified as "benign," "of uncertain malignant potential," or "malignant." Small PEComas without any worrisome histologic features are most likely benign. PEComas with nuclear pleomorphism alone ("symplastic") and large PEComas without other worrisome features have uncertain malignant potential. PEComas with two or more worrisome histologic ...
The Cancer Genome Atlas described four major genomic groups of endometrial carcinomas, including a POLE ultramutated subtype comprising B10% of endometrioid adenocarcinoma, characterized by POLE exonuclease domain mutations, ultrahigh somatic mutation rates, and favorable outcome. Our aim was to examine the morphological and clinicopathological features of ultramutated endometrial carcinomas harboring somatic POLE exonuclease domain mutations. Hematoxylin and eosin slides and pathology reports for 8/17 POLEmutated endometrial carcinomas described in the Cancer Genome Atlas study were studied; for the remaining cases, virtual whole slide images publicly available at cBioPortal (www.cbioportal.org) were examined. A second cohort of eight POLE mutated endometrial carcinomas from University of Calgary was also studied. Median age was 55 years (range 33-87 years). Nineteen patients presented as stage I, 1 stage II, and 5 stage III. The majority of cases (24 of the 25) demonstrated defining morphological features of endometrioid differentiation. The studied cases were frequently high grade (60%) and rich in tumor-infiltrating lymphocytes and/or peri-tumoral lymphocytes (84%); many tumors showed morphological heterogeneity (52%) and ambiguity (16%). Foci demonstrating severe nuclear atypia led to concern for serous carcinoma in 28% of cases. At the molecular level, the majority of the Cancer Genome Atlas POLE-mutated tumors were microsatellite stable (65%), and TP53 mutations were present in 35% of cases. They also harbored mutations in PTEN (94%), FBXW7 (82%), ARID1A (76%), and PIK3CA (71%). All patients from both cohorts were alive without disease, and none of the patients developed recurrence at the time of follow-up (median 33 months; range 2-102 months). In conclusion, the recognition of ultramutated endometrial carcinomas with POLE exonuclease domain mutation is important given their favorable outcome. Our histopathological review revealed that these tumors are commonly high grade, have obvious lymphocytic infiltrates, and can show ambiguous morphology. As they frequently harbor TP53 mutations, it is important not to misclassify them as serous carcinoma.
We present clinicopathologic data on 10 pulmonary myxoid sarcomas, which are defined by distinctive histomorphologic features and characterized by a recurrent fusion gene, that appear to represent a distinct tumor entity at this site. The patients [7 female, 3 male; aged 27 to 67 y (mean, 45 y)] presented with local or systemic symptoms (n=5), symptoms from cerebral metastasis (1), or incidentally (2). Follow-up of 6 patients showed that 1 with brain metastasis died shortly after primary tumor resection, 1 developed a renal metastasis but is alive and well, and 4 are disease free after 1 to 15 years. All tumors involved pulmonary parenchyma, with a predominant endobronchial component in 8 and ranged from 1.5 to 4 cm. Microscopically, they were lobulated and composed of cords of polygonal, spindle, or stellate cells within myxoid stroma, morphologically reminiscent of extraskeletal myxoid chondrosarcoma. Four cases showed no or minimal atypia, 6 showed focal pleomorphism, and 5 had necrosis. Mitotic indices varied, with most tumors not exceeding 5/10 high-power fields. Tumors were immunoreactive for only vimentin and weakly focal for epithelial membrane antigen. Of 9 tumors, 7 were shown to harbor a specific EWSR1-CREB1 fusion by reverse transcription-polymerase chain reaction and direct sequencing, with 7 of 10 showing EWSR1 rearrangement by fluorescence in situ hybridization. This gene fusion has been described previously in 2 histologically and behaviorally different sarcomas: clear cell sarcoma-like tumors of the gastrointestinal tract and angiomatoid fibrous histiocytomas; however, this is a novel finding in tumors with the morphology we describe and that occur in the pulmonary region.
Spontaneous regression of testicular germ cell tumors (GCTs) is a well-recognized phenomenon but has been incompletely characterized. Many pathologists are not familiar with the findings that support a diagnosis of a "burnt-out" primary in a patient with metastatic GCT. We therefore report the clinical, gross, and histologic findings in 42 cases of testicular GCT that showed either complete (26) or greater than 50% scarring (16). Thirty-seven patients (88%) had either known GCT metastasis or some residual testicular GCT, and none had treatment before orchiectomy. The patients were 17 to 67 years old, with a median of 32. Thirty presented with symptoms of metastasis, 7 with a testicular mass, 2 with elevated human chronic gonadotropin, and 1 with testicular pain. In 2 patients the presentation was unknown. Two patients had prior orchiopexy; another had an intraabdominal testis, and 2 others had prior contralateral seminoma (20 and 42 years previously). Gross descriptions in 37 cases identified white to tan scars, 0.6 to 2.4 cm, in 33. These were circumscribed in 16, with 15 of these having nodular or multinodular configurations and 1 a band-like appearance. In 9 cases the scar was ill defined or stellate, and in 8 cases no further details concerning the scar configuration were available. In 4 cases no scar was apparent; 2 of these had received intraoperative biopsy. Microscopically, all cases showed circumscribed to irregular foci of scarring, distinct from the adjacent parenchyma, in association with widespread testicular atrophy. Other common features were lymphoplasmacytic infiltrates in the scars (37/42) and "ghost" tubules in scars (31/42). Less common features in the scars included angiomatous foci (22/42), siderophages (15/42), and coarse intratubular calcifications (6/42); in the surrounding testis they included intratubular germ cell neoplasia, unclassified (IGCNU) (22/42), Leydig cell prominence (18/42), and necrosis (5/42). Tubular microliths occurred in 13 cases, 12 peripheral to the scar and 1 within it. Metastases in 31 cases were: pure seminoma (17, 3 with residual testicular seminoma), mixed GCT with seminoma (4, 3 with residual testicular seminoma), mixed nonseminomatous GCT (4, 3 with residual testicular GCT), pure embryonal carcinoma (2), pure teratoma (2, 1 with residual testicular teratoma), and pure yolk sac tumor (2). In 5 cases with clinically diagnosed metastases, there was no histologic documentation of the nature of the metastatic tumor. Testicular tumors in the remaining 6 cases having residual primaries without concomitant metastases were pure seminoma (3), mixed GCT with seminoma (2), and pure embryonal carcinoma (1). The most specific histologic findings of a regressed GCT are a distinct scar in association with either IGCNU or coarse intratubular calcifications; however, many cases lack the latter 2 features. In such cases additional features supportive of regressed GCT include testicular atrophy, microlithiasis and, in the scar, lymphoplasmacytic infiltrates and prominent vasculari...
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