Proliferative nodules arising within XXXX : a histologic, immunohistochemical, and molecular analyses of 43 cases.

@entity1 @entity66 @entity10158 @entity984 @entity8205 @entity7174 @entity8497 @entity817 @entity8498 @entity320
The histopathologic interpretation of proliferative nodules (PNs) in @entity8205 can present significant challenges as some PNs may exhibit atypical features that make the distinction from @entity320 . We compared histologic features, Ki-67%, PHH3, and CD117% expression levels by immunohistochemistry in 18 benign and 25 atypical PNs (from 41 @entity1 ) with that of background @entity7174 (of these 43 cases), 10 @entity7174 , and 3 dermal @entity320 arising in @entity66 . In addition, we evaluated the presence of @entity817 , @entity10158 , @entity8498 , @entity984 , and @entity8497 mutations in all groups using the SNaPshot Multiplex System. Follow-up was available on 19 @entity1 (9 benign and 10 atypical PNs) (range, 2 to 20 y; median, 8 y) and all were alive with no evidence of disease. The specific histologic features of atypical PNs, such as sharp demarcation (P<0.001), expansile growth (P<0.001), epidermal effacement (P<0.001), nuclear pleomorphism (P<0.001), and increased mitoses (P<0.001), differed significantly from those of benign PNs. Immunohistochemical results showed that Ki-67% and PHH3 scores, but not CD117% expression, were significantly higher (P<0.05) in atypical PNs. Molecular analyses showed that the PNs and background @entity8205 of the giant @entity7174 possess more frequent @entity8497 mutations and infrequent @entity817 mutations when compared with those of the remaining cases. These findings suggest that histologic features and Ki-67 and PHH3 expression levels are the strongest parameters to distinguish between benign versus atypical PNs. The immunohistochemical results suggest that atypical PNs are distinct borderline lesions residing between benign PNs and dermal @entity320 . Although numerous mutations are detected in the samples, the diagnostic use of molecular analysis in this regard is limited.
