UNASSIGNED: Periocular sebaceous carcinoma (PSC) remains a common diagnostic pitfall both clinically and histomorphologically. PRAME (preferentially expressed antigen in melanoma) has been studied in the various neoplasms as proposed as diagnostic and therapeutic markers. PRAME is expressed in normal sebaceous units and in some sebaceous lesions; however, its utility in sebaceous carcinoma diagnosis has not yet been extensively investigated. We conducted a 13-year retrospective review of the patients diagnosed with PSC at the National Specialist Ophthalmic Pathology Service in Liverpool. Herein, we report the histomorphological and immunohistochemical (IHC) features of these tumors, particularly PRAME expression in this cohort.
UNASSIGNED: Thirty-one PSC cases diagnosed between 2009 and 2022 were retrieved from the histopathology archives. Twenty cases diagnosed as invasive PSC and 11 cases with in situ PSC were included. The hematoxylin and eosin (H&E) slides and previously performed IHC slides were reviewed; clinical information data were obtained. Cases with an adequate tissue were also stained for PRAME (preferentially expressed antigen in melanoma) and adipophilin (if not already performed).
UNASSIGNED: In total, there were 24 females and 7 males diagnosed with PSC, ranging from 55 to 90 years (median, 78 years). The types of specimens received were 11 conjunctival mapping biopsies, 19 excisions/wedge resections, and 1 orbital exenteration. The eyelid was the commonest site involved (n = 24), followed by eyelid with conjunctiva (3), and conjunctiva alone (4). All patients presented with the clinical suspicion of malignancy. Histologically, 11 invasive PSC (55%) exhibited poorly differentiated morphology, composed of predominantly atypical basaloid cells with minimal sebocytic differentiation; 9 cases (45%) were moderately differentiated with noticeable finely multivacuolated cytoplasm; and 3 (15%) showed associated comedo necrosis. Most invasive PSC showed moderate-to-brisk mitotic activities. Of those cases with available immunostains (n = 31), 25 (80.6%) expressed adipophilin; 18 (58.1%) Ber-EP4; 14 (45.2%) epithelial membrane antigen (EMA); and 5 (16.1%) both androgen receptor and perforin positivity. PRAME expression was seen in normal sebaceous glands; however, only (5/19; 26%) of invasive PSC showed focal weak-to-moderate PRAME positivity, and mostly in moderately differentiated tumors. None of the in situ PSCs were PRAME-positive.
UNASSIGNED: Most PSCs are moderate-to-poorly differentiated. Although PRAME is expressed in normal sebaceous units, it appears less useful as diagnostic marker for PSC, especially in poorly differentiated tumors. In difficult cases, panels of IHC studies (adipophilin, Ber-EP4, and EMA) achieve a definitive diagnosis.

Loss of the polybromo-1 (PBRM1) protein has been expected as a possible biomarker for clear cell renal cell carcinoma (ccRCC). There is little knowledge about how PBRM1 immunohistochemical expression correlates with the histomorphological features of ccRCC and the endothelial expression of tumor vasculature. The present study evaluates the association of architectural patterns with the PBRM1 expression of cancer cells using a cohort of 425 patients with nonmetastatic ccRCC. Furthermore, we separately assessed the PBRM1 expression of the endothelial cells and evaluated the correlation between the expression of cancer cells and endothelial cells. PBRM1 loss in cancer cells was observed in 148 (34.8%) patients. In the correlation analysis between architectural patterns and PBRM1 expression, macrocyst/microcystic, tubular/acinar, and compact/small nested were positively correlated with PBRM1 expression, whereas alveolar/large nested, thick trabecular/insular, papillary/pseudopapillary, solid sheets, and sarcomatoid/rhabdoid were negatively correlated with PBRM1 expression. PBRM1 expression in vascular endothelial cells correlated with the expression of cancer cells (correlation coefficient = 0.834, p < 0.001). PBRM1 loss in both cancer and endothelial cells was associated with a lower recurrence-free survival rate (p < 0.001). Our PBRM1 expression profile indicated that PBRM1 expression in both cancer and endothelial cells may be regulated in an orchestrated manner.

Evidence from current studies show that squamous cell carcinomas at oral and oropharyngeal sites are distinct and unique, with their own separate etiopathogenesis, treatment, and prognosis. The aim of this work is to correlate p16 immunohistochemical expression with histomorphological features suggestive of HPV infection in oral and oropharyngeal squamous cell carcinoma. A total of 50 consecutive biopsy cases of oral squamous cell carcinoma (OSCC) and 50 consecutive biopsy cases of oropharyngeal squamous cell carcinoma (OPSCC) were evaluated for features suggestive of HPV infection like focal basaloid appearance, nests, and lobules of tumor cells with pushing borders, absence of stromal reaction, central necrosis, focal lymphoepithelial morphology, presence of koilocytes, and non-keratinizing or hybrid morphology. Immunostaining was performed using p16 monoclonal antibody (clone mouse 16P04). Only cases showing a moderate (2+) to high intensity (3+) staining in more than 75% cells were taken as p16 immunopositive. The histological features were correlated with p16 immunopositivity. A total of 18/50 (36%) cases of oral squamous cell carcinoma and 27/50 (54%) cases of oropharyngeal squamous cell carcinoma were p16 immunopositive. On statistical analysis, only nests/lobules with pushing borders were found to have a significant correlation with p16 immunopositivity (P value = 0.0012) for OSCC cases. For OPSCC cases, four histological features namely nests and lobules with pushing borders (P value = 0.0001), focal basaloid appearance (P value = 0.0041), lymphoepithelial morphology (P value = 0.0029), and non-keratinizing/hybrid morphology (P value = 0.0141) had a significant correlation with p16 immunopositivity. Histomorphological features are more helpful in predicting p16 immunopositivity in OPSCC than OSCC.