Benign eccrine poroma of the dorsum of the hand: predilection for the nail fold and P53 positivity

Altered Rb, p16, and p53 expression is specific for porocarcinoma relative to poroma

“…Our study further benefits from correlation with mutation status of the relevant genes in a subset of cases. Some previous reports have not found a significant difference between poromas and porocarcinomas in the percentage of cells labeling for p53 [9][10][11][12][13] ; however, many of these studies did not account for staining intensity. In our cohort, a high percentage of cells in poromas showed weak p53 staining; evaluation of p53 staining intensity was therefore critical for distinguishing mutation-associated p53 overexpression in porocarcinoma from diffuse but predominantly weak expression in poromas.…”

“…Previous studies have examined p53, Rb, or p16 staining in the context of poromas and/or porocarcinomas, although to our knowledge our study is the first to rigorously examine the combined performance of all three markers. Our study further benefits from correlation with mutation status of the relevant genes in a subset of cases.…”

“…Previous immunohistochemical studies on these markers in poromas and porocarcinomas have been limited and yielded contradictory results. 4,[8][9][10][11][12][13][14] Our initial studies indicated that p53 expression may correlate with TP53 mutation status in porocarcinomas, 4 with dominant negative mutations associated with overexpression of p53 protein predicted to lack tumor suppressor activity, and truncating mutations associated with diffuse loss of p53 expression. We investigated whether p53, Rb, and p16 marker expression correlated with mutational status in porocarcinomas, and whether a panel immunohistochemistry approach including these tumor suppressors distinguished porocarcinomas from poromas.…”

An Unusual Periungual Lesion

“…Our case is unusual because, clinically, the lesion appeared to arise from the nail bed. Nail-related eccrine poromas are rare; there are only 7 publications reported in the literature: 2 cases were periungual [7,8], 3 were affecting the nail fold [9,10,11], 1 was subungual [12], and 1 was affecting the hyponychium and the lateral nail fold [13]. …”

Eccrine Poroma Clinically Mimicking Ingrowing Toenail Complicated with Granulation Tissue

“…Firstly, the protruding papule looked very similar to the granulation tissue caused by ingrowing toenails. Secondly, eccrine poroma is rarely observed on the dorsum of the hands and feet3. Lastly, as the patient had ingrowing toenails previously, most physicians would have diagnosed the lesion as an ingrowing toenail complicated by granulation tissue.…”