Monozygotic Twins with Congenital Guttate Leukoderma

KAZUYOSHI FUKAI, ATSUKO KADOYA, HIROYUKI TERAMAE, and MASAMITSU ISHII

Citation Osaka City Medical Journal. Issue Date 2005-06 Type Journal Article Textversion Publisher © Osaka City Medical Association. Right https://osakashi-igakukai.com/.

Placed on: Osaka City University Repository

KAZUYOSHI FUKAI, ATSUKO KADOYA, HIROYUKI TERAMAE, and MASAMITSU ISHII. Monozygotic Twins with Congenital Guttate Leukoderma. Osaka City Medical Journal. 2005, 51, 33- 36 Osaka City Med. J. Vol. 51, 33-36, 2005

KAZUYOSHI FUKAI,ATSUKO KADOYA,HIROYUKI TERAMAE, and MASAMITSU ISHII

Department of Dermatology, Osaka City University, Graduate School of Medicine

Abstract We report here two cases of congenital guttate hypomelanotic macules observed in monozygotic twins. They both have had discrete leukoderma regions in the axillae, inguinal region and lower abdomen since birth. The size and the shape did not change until at least the age of nine. Development of both patients was otherwise normal. The split-DOPA reaction revealed no DOPA-positive melanocytes in the hypomelanotic skin, but electron microscopy revealed melanocytes that were regular but decreased in number. Cytogenetic analysis of the peripheral leukocytes revealed normal female karyotype in both cases. Considering the unique pattern of the leukoderma lesions which occurred in both monozygotic twins, this might be a new clinical entity.

Key Words: Guttate hypomelanosis; Monozygotic twins

Introduction Multiple guttate hypomelanotic macules may be associated with tuberous sclerosis, pityriasis lichenoides chronica, Darier’s disease, Grover’s disease, dyschromic amyloidosis, or keratosis punctata1). They may be simply idiopathic, and generally occur as a senile phenomenon. Here, we describe what we believe to be the first case of congenital multiple guttate hypomelanotic macules developing in both of two monozygotic twins, who have none of the above skin disorders.

Case report A six-year-old girl was referred to our clinic for evaluation of numerous guttate hypomelanotic macules on the axillae, inguinal region and the lower abdomen. They were about 4 to 6 mm in diameter, well demarcated, and oval to round in shape (Fig. 1). These leukoderma lesions seemed to be present since birth and became evident at the age of six months, and gradually increased in number until the age of one year. Since then, the leukoderma lesions have been stable, and have not changed in size and number. She was otherwise healthy. Motor and psychological development was normal. There were no relatives with pigmentary disorders. She had a monozygotic twin, who also had very similar leukoderma lesions since birth (Fig. 2). The sister had congenital clubfoot of her left foot, but was otherwise healthy. Neither of them had a cutaneous change suggestive of Darier’s disease, punctate keratosis, tuberous sclerosis, or

Received March 24, 2004; accepted October 12, 2004. Correspondence to: Kazuyoshi Fukai, MD. Department of Dermatology, Osaka City University, Graduate School of Medicine, 1-4-3 Asahimachi, Abeno-ku, Osaka 545-8585, Japan Tel: +81-6-6645-3826; Fax: +81-6-6645-3828 E-mail: [email protected]

- 33 - Fukai et al pityriasis lichenoides chronica. The parents were not related. The split-DOPA reaction revealed no DOPA-positive melanocytes in the leukoderma, but regular distribution of such melanocytes in the adjacent normally pigmented skin. Electron-microscopic examination revealed decreased but regularly distributed melanocytes in the epidermis. The melanocytes were basically normal in shape, and the melanization within melanosomes also appeared normal (Fig. 3). Cytogenetic analysis of the peripheral leukocytes revealed a normal female 46, XY karyotype in both cases.

Figure 1. Small oval to round circumscribed hypopigmented macules in the inguinal region.

Figure 2. Hypopigmented macules were distributed similarly in the inguinal region and the lower abdomen (and the axillae, not shown) in both of the monozygotic twins (left, patient; right, sister).

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Figure 3. Electron microscopy showed that melanocytes were regularly distributed but in reduced number in the leukoderma lesions. Melanosomes within the melanocytes appeared as normally melanized (×15000).

Discussion We describe here a twin patients who had congenital multiple guttate hypomelanosis in the axillae, inguinal region and lower abdomen. There were no DOPA-positive melanocytes within the white areas, but electron microscopy revealed regularly distributed melanocytes, in which melanization was normal. These findings may be similar to nevus depigmentosus2). However, nevus depigmentosus does not usually occur in exactly the same distribution in monozygotic twins. Tuberous sclerosis is sometimes associated with confetti-like tiny white macules that range from 1 to 3 mm in size. Confetti-like lesions have a predilection for the legs, and are considered as characteristic of tuberous sclerosis3-5). The present cases exhibited no other cutaneous manifestations suggestive of tuberous sclerosis, e.g., Shagreen patches, and ash-leaf hypopigmented macules, facial angiofibromas or periungual fibromas. Since the size of the confetti-like lesions in tuberous sclerosis is generally much smaller than that in our cases, and its location is often the legs, and most importantly that there are no associated findings suggestive of tuberous sclerosis, the diagnosis of tuberous sclerosis also seems unlikely. Guttate hypomelanotic macules are associated with punctate keratosis of the palms and soles6). However, in our cases, the palms and soles were normally keratinized. A chromosomal abnormality was reported in one patient with guttate hypomelanosis in a previous literature7). However, both of our patients had a normal female karyotype. Amyloidosis may be a cause of guttate hypomelanosis8), but the electron microscopic examination in this study did not reveal the presence of amyloid in the papillary dermis. Darier’s disease may be associated with small localized leukoderma in dark-skinned individuals9-13). It is characterized histologically by the presence of acantholytic dyskeratosis. In our cases, no acantholysis was observed in thick section of specimens embedded for electron microscopy. Clinically, the patients were free of red or follicular papules on the entire body surface. Therefore, none of the above diseases are likely diagnosis for our two cases. A very unique feature of the present cases are the presence of numerous guttat hypomelanotic macules on the axillae and inguinal region since birth, and this condition occurring in both of the monozygotic twins. There are no other family members with the same pigmentary condition. Although it is too early to determine this is a genetic disorder, the guttate leukoderma occurred

- 35 - Fukai et al in monozygotic twins. Therefore, it is tempting to speculate that this is of simple Mendelian inheritance. If these conditions are autosomal dominantly inherited, a half the offsprings of the patients should carry the same pigmentary changes. We may be able to witness in 20 years later. If the guttate leukoderma was due to autosomal recessive disorder, we need to collect such families to do linkage analysis, preferably consanguineous families, which may facilitate homozygosity mapping. We reported here very unique congenital guttate leukoderma observed in both monozygotic twins. We believe that these conditions are not reported before, and represent a new clinical entity. Accumulations of similar cases are awaited.

Acknowlegdement This study was supported in part by the grant-in-aid from the ministry of education, sports and culture of Japan (#15591187 to KF).

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