Hystrix-like ichthyosis and deafness (HID) syndrome is a rare ectodermal dysplasia characterized by erythrokeratoderma and hearing impairments. HID syndrome is a nonocular variant of keratitis ichthyosis deafness (KID) syndrome caused by an autosomal dominant mutation in the gap junction protein β 2 (GJB2) gene. The GJB2 gene encodes connexin 26, a transmembrane protein involved in cell–cell attachment in almost all tissues. We report a case of a 25-year-old man with generalized hyperkeratotic plaques, diffuse palmoplantar keratoderma, and nail deformities since birth. The patient also had a history of recurrent bacterial skin infections in the existing hyperkeratotic lesions. Histopathological examination revealed compact hyperkeratosis and irregular acanthosis in the epidermis, along with upper dermal lymphocytic infiltration. Audiometry revealed high-frequency sensorineural hearing loss. Genetic analysis revealed a missense mutation in the GJB2 gene. Based on clinicopathological findings and genetic testing, HID syndrome was diagnosed.

Weathering nodules are benign skin conditions of the ear typically occurring in patients with a history of persistent sun exposure. Clinically, they appear as multiple localized, skin-colored to whitish papules or nodules in the ear helix. Histopathologically, weathering nodules are characterized by chondroid metaplasia with spurs of fibrous tissue extending upward from the disrupted perichondrium of the underlying pinna cartilage. We report the case of a 19-year-old man who presented with multiple localized whitish papules on the right ear helix for a month. The lesions were asymptomatic and accompanied by a blanch sign. Histopathological examination revealed chondroid metaplasia in the dermis, separate from the pinna cartilage. Based on the clinicopathological findings, weathering nodules of the ear was diagnosed.

Acanthosis nigricans (AN) is characterized by velvety hyperpigmented plaques, usually observed in skin folds. The different types of the condition include obesity-associated, syndromic, drug-induced, malignancy-related, and other types of AN. AN, an FGFR3 gene mutation-related disease, is associated with varying degrees of skeletal disorders. FGFR3 gene mutations are known to cause excessive inhibition of chondrocyte growth and keratinocyte proliferation, which is responsible for AN development. To our knowledge, only a small number of cases of AN with hypochondroplasia due to FGFR3 gene mutation (p.Lys650Thr) have been described in the literature. However, there are no reports of genetically confirmed AN with hypochondroplasia in Korea. Physicians should consider syndromic AN when symptoms develop at an early age or when associated skeletal anomalies are present.