Background: Ber-EP4 is an immunohistochemical marker targeting epithelial cell adhesion molecule and is widely applied in the diagnosis of cutaneous basal cell carcinoma (BCC). Although highly sensitive, variability in expression level and staining distribution may complicate interpretation in routine practice. Objective: This study aimed to characterize Ber-EP4 expression and staining patterns in cutaneous BCC and to assess their associations with clinicopathological features. Materials and methods: Sixty surgically excised cases of cutaneous BCC were retrospectively analyzed. Ber-EP4 immunohistochemistry was performed using an automated staining platform. Expression was evaluated according to the proportion of positive tumor cells, and staining patterns were classified based on spatial distribution. Associations between Ber-EP4 expression and clinicopathological features were analyzed. Results: All cases demonstrated Ber-EP4 positivity, with a mean percentage of Ber-EP4–positive tumor cells per case of 78.1%. High-level expression was observed in 68.3% of cases. Diffuse staining was the predominant pattern, identified in 85.0% of tumors, while nondiffuse patterns accounted for the remaining 15.0%. Ber-EP4 expression showed no significant associations with most clinicopathological variables; however, ulceration was significantly associated with reduced Ber-EP4 expression (aOR = 12.05; 95% confidence interval, 2.41–60.15; P = 0.002). Conclusions: Ber-EP4 is a highly sensitive immunohistochemical marker for cutaneous BCC, showing predominantly diffuse expression across diverse clinicohistologic contexts. However, reduced expression in ulcerated tumors and the presence of nondiffuse staining patterns highlight potential diagnostic pitfalls, particularly in superficially sampled lesions. These findings underscore the need for cautious interpretation and integrated histomorphological and immunohistochemical assessment to ensure diagnostic accuracy.

Background: PRAME immunohistochemistry is a useful adjunct in distinguishing melanoma from benign melanocytic lesions, but its clinicopathologic associations remain incompletely understood, particularly in underrepresented populations. Methods: This retrospective study included 90 primary melanomas and 90 melanocytic nevi from a Vietnamese cohort. PRAME expression (clone EPR20330) was assessed using a semi-quantitative scoring system: 0 (0%), 1+ (1–25%), 2+ (26–50%), 3+ (51–75%), and 4+ (> 75% of tumor cells with nuclear positivity), with 4 + defined as high expression. Diagnostic performance was evaluated using receiver operating characteristic (ROC) analysis, and associations with clinicopathologic variables were analyzed using logistic regression. Results: The mean age of melanoma patients was 56.4 ± 15.9 years, with a median tumor size of 30 mm. Nodular melanoma was the most common subtype (60%), and mucosal melanoma accounted for 15.6%. Adverse features were common, including Breslow thickness > 1 mm (87.8%), mitotic rate > 1/mm² (85.6%), and ulceration (36%). High PRAME expression was observed in 73.3% of melanomas, whereas 97.8% of nevi were negative and none showed PRAME ≥ 2+. PRAME demonstrated excellent diagnostic performance (AUC 0.936), with sensitivity, specificity, and accuracy of 87.8%, 97.8%, and 92.8% at a cutoff of ≥ 1+. Tumor size > 12 mm was independently associated with high PRAME expression in the overall cohort but not in cutaneous melanoma. No statistically significant associations were observed between PRAME expression and tumor stage in cutaneous melanoma. Conclusions: In this predominantly advanced-stage Vietnamese cohort, PRAME immunohistochemistry showed high sensitivity and specificity in distinguishing melanoma from nevi; its performance in early or thin melanomas and its broader clinicopathologic significance remain to be clarified in future studies.

Adenocarcinoma is the predominant malignant tumor of the prostate, while primary prostatic leiomyosarcoma is an exceptionally rare and highly aggressive mesenchymal neoplasm. The synchronous presence of both entities is extremely uncommon and has been, to our knowledge, described in only a few cases. We describe a 50-year-old man with persistent lower urinary tract symptoms and mildly elevated prostate-specific antigen. Imaging demonstrated two distinct intraglandular lesions. Histopathology and immunohistochemistry confirmed acinar adenocarcinoma and leiomyosarcoma in separate foci. Laparoscopic radical prostatectomy was performed; positive sarcomatous margins prompted adjuvant radiotherapy. Integrated clinical, radiologic, and pathologic assessment is essential for accurate diagnosis and management.