Int J Gynecol Pathol. 2021 Sep 1;40(5):482-486. doi: 10.1097/PGP.0000000000000726.
Pilomatrix carcinoma (PC) is a rare malignant variant of pilomatrixoma, a skin adnexal tumor originating from hair matrix cells. It is most often located in the head, neck region, upper back and upper extremities. PC has a locally aggressive behavior but metastasis only occur in 10% of cases. Mutations in CTNNB1, the encoding gene of beta-catenin, have been found in both pilomatrixoma and PC, but other molecular alterations are unknown. The authors present a case of PC in the clitoris, the third known reported case located on the external genitalia. The tumor followed an unusual clinical course with the development of multiple metastases. Next-generation sequencing analysis of the tumor identified, in addition to a characteristic CTNNB1 mutation, pathogenic mutations in PTEN, PIK3CA, and ARID1A, which could explain the aggressive course of the disease. The diagnostic criteria of PC and the differential diagnoses of this unusual tumor in the genital area are discussed.
毛母质瘤(PC)是毛母质瘤的一种罕见恶性变异,毛母质瘤是一种起源于毛发基质细胞的皮肤附属器肿瘤。它最常发生在头部、颈部、上背部和上肢。PC 具有局部侵袭性,但只有 10%的病例发生转移。CTNNB1 基因突变,即β-连环蛋白的编码基因,已在毛母质瘤和 PC 中发现,但其他分子改变尚不清楚。作者报告了一例发生在阴蒂的 PC,这是第三例已知位于外生殖器的病例。肿瘤的临床过程不寻常,发生了多处转移。肿瘤的下一代测序分析发现,除了特征性 CTNNB1 突变外,还存在 PTEN、PIK3CA 和 ARID1A 的致病性突变,这可以解释疾病的侵袭性过程。讨论了 PC 的诊断标准以及该罕见肿瘤在生殖器区域的鉴别诊断。