abnormal genes caused by a mutation which merges a part of the YAP1 gene fused to part of either the Nuclear protein in testis gene (also termed the NUTM1 gene) or the MAML2 gene to form the YAP1::NUTM1 and YAP::MAML2 fusion genes, respectively. Rarely, they may also contain a WWTR1::NUTM1 fusion gene. The YAP1::MAML2 fusion gene is detected in ~63% of poromas, the YAP1::NUTM1 fusion in 20.2% to 66% of poromas, and the WWTR1::NUTM1 fusion gene in 1% of poromas. YAP1  and WNTR1 fusion genes have been implicated in the initiation, aggressiveness, metastasis, and/or therapy resistance of various neoplasms. Studies are needed to determine if they play a role in the development and/or progression of poromas. Diagnosis
The great diversity, rarity, and complex terminology of poromas make their diagnosis challenging. They have been misdiagnosed as other types of skin tumors including porocarcinomas, basal cell carcinomas, pyogenic granulomas, skin tags, plantar warts (i.e. warts on the palms or soles), fibromas, hemangiomas, pigmented moles, seborrheic keratosis, trichilemmomas, melanomas, Kaposi sarcomas, and other adnexal tumors. Poromas are typically diagnosed based on their clinical presentation; microscopic histopathology showing tumor tissues consisting of poroid, cuticular, and/or clear cells; and, in unclear cases, the presence of tumor cells that express a YAP1::NUTM1, YAP::MAML2, and/or WWTR1::NUTM1 fusion gene. However, these fusion genes also occur in porocarcinomas and cannot be used to differentiate poromas from their malignant counterpart. Poromas and porocarcinomas are distinguished based on their clinical findings and histopathology, e.g.
a higher Ki67 labeling index and aberrant expression of p53, RB, and p16 proteins are more frequent in porocarcinoma (see Diagnosis of porcarcinomas). Dermatoscopy, particularly when revealing a "leaf- and flower-like pattern" in a skin tumor, has been used as a strong indicator that the lesion is a poroma, but confirmation of this diagnosis ultimately relies on histopathological analyses.There is no clear-cut evidence that diagnosing a poromas variant type carries any clinical or therapeutic significance. Treatment
Superficial poroma tumors have been treated by shaving (i.e. removal using a sharp razor) or electrosurgical destruction. Deeper lesions have been removed by excisional biopsy (i.e. a procedure in which an entire tumorous or suspicious area is removed) or simple surgical excision. Since poromas are almost always benign tumors and rarely recur  after their removal, these treatments are in general curative. See also
Porocarcinoma
Hidradenoma


== References ==