Homozygous Missense Mutation in the LIPH Gene Causing Autosomal Recessive Hypotrichosis Simplex in a Chinese Patient

improved. The latter treatment was followed by topical steroid and topical tacrolimus, with 0.1% applied on alternate days. After 1 month of topical treatment, some papular lesions had flattened. Most lesions, except for several papules, had cleared; however, hyperpigmentation remained after 3 months of topical therapy. Our case is unique in that the skin lesions were arranged in a zosteriform pattern along the right T12 dermatome. In rare instances, unilateral involvement along Blaschko’s line is seen. Even the zosteriform distribution is extremely rare, with only one case of zosteriform distribution reported. This unusual zosteriform pattern may be elucidated by an isotopic response, although the exact pathogenesis remains unknown. In our case, the patient had no preceding skin disease, such as herpes zoster or contact dermatitis. The pathogenesis of TAD is not clearly defined. Recently, it has been postulated that the acantholysis may be caused by leakage of molecules from the eccrine duct to the adjacent epidermis. In addition, it has been also associated with many other medical conditions including chemotherapy, bone marrow transplantation, pregnancy and hematological diseases. However, in our case, there was no relationship with any of the above-mentioned factors. Chistoher et al. reported the relation with mannose-binding lectin (MBL) and the MBL-associated serine protease (MASP) pathway. MBL and MASP are an essential part of innate immunity. With regard to the unilateral involvement, some authors have suggested that such conditions may act as precipitating factors on a genetically disposed epidermis. In localized cases, as in ours, this hypothesis could imply postzygotic somatic mutations in dermatomes or along Blaschko’s lines. In addition, we may postulate that the patient had irritated the skin lesions by being prone to not only scratch, but to accumulate sweat. Transient acantholytic dermatosis shows four main histological patterns: (i) acantholysis with spongiosis; (ii) Darier’s disease-like pattern; (iii) pemphigus-like pattern; and (iv) Hailey– Hailey disease-like pattern. In our case, the histological type of TAD is supposed to be acantholysis with spongiosis due to absence of corps ronds and grain or dilapidated brick wall. The histology of TAD shows chiefly focal acantholysis and dyskeratosis. Therefore, TAD should be differentiated from acantholytic dermatoses such as pemphigus, Hailey–Hailey disease and Darier’s disease. It is important to differentiate TAD from the other acantholytic dermatoses in which the focal nature of the histological changes and the mixture of patterns exist. Especially, the differential diagnosis with Darier’s disease is difficult not only histologically but also clinically. We favored the diagnosis of TAD because of the late onset of the disease and the absence of any family history. Therefore, a clinical correlation may be helpful if the diagnosis is difficult to make on the basis of histological results. In this case, the patient had a good response to topical steroid and tacrolimus treatment, although we could not exclude the possibility that the skin lesions had undergone spontaneous remission. The follow up and treatment are often difficult to evaluate secondary to the fluctuant course of the disease. Approximately half of patients with TAD respond to topical or systemic steroids, and have an induced, sustained remission.