Abstract

We describe a case of perineal squamous cell carcinoma (SCC) arising in a porokeratosis in a young woman with keratitis-ichthyosis-deafness syndrome (KID). KID was diagnosed at age 6 months in the setting of congenital neurosensory deafness and mucocutaneous candidiasis. Over time, the patient developed ocular vascularizing keratitis, porokeratotic eccrine duct and hair follicle nevi (PEHFN) and SCC of the buccal mucosa metastatic to local lymph nodes. She subsequently presented in her 30s with several pink hyperkeratotic plaques in the perineal region. Shave biopsy of the largest lesion demonstrated a well differentiated SCC arising in a porokeratosis. Punch biopsies of two additional perineal lesions demonstrated porokeratoses. The patient’s SCC was treated with Mohs surgery and subsequent cholesterol-lovastatin cream to the perineum and vaginal skin with significant improvement in porokeratoses. While the characteristic features of KID syndrome include ocular vascularizing keratitis, erythrokeratoderma, and congenital neurosensory deafness, KID also confers an increased risk of infection and malignancy. SCC is estimated to occur in approximately 15-20% of KID patients. Predilection of KID patients to mucosal and cutaneous SCC may be due to impaired integrity of gap junctions leading to increased cellular proliferative potential. Although altered connexin 26 expression is seen in SCC, it does not fully explain the porokeratoses in the perineal region in our patient. Although PEHFN and mosaic forms have been reported in patients with connexin 26 mutations, classic porokeratoses without follicular and eccrine adnexal extension are not a common finding in KID syndrome. Our patient experienced improvement in porokeratoses following topical cholesterol-lovastatin. The mechanism of this drug is to prevent the accumulation of toxic metabolites in the mevalonate pathway, which is typically disrupted in familial porokeratoses but not known to be affected in KID syndrome.

Financial Disclosure:
No current or relevant financial relationships exist.