Dermatology Online Journal

Multiple congenital familial smooth muscle hamartoma in two siblings
Juan García-Gavín MD, Lidia Pérez-Pérez MD, Francisco Allegue, Alberto Pérez-Pedrosa, Jose Antonio Ortíz-Rey, Ánder Zulaica PhD
Dermatology Online Journal 18 (5): 7

1. Department of Dermatology
2. Department of Pathology
University Hospital Complex of Vigo, Pontevedra, Spain

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Abstract

Smooth muscle hamartoma (SMH) is a cutaneous malformation mainly composed of a disorganized proliferation of normal muscle fibers that arise from arrector pili. It usually presents as a single congenital lesion that frequently involves the back and the lower limbs. Unusual clinical presentations, such as atypical localizations, multiple disseminated lesions, and generalized forms have been rarely described. In 2001, Gualandri et al. reported the presence of multiple SMH in three members of the same family, namely two brothers and their mother. This is, as far as we know, the only familial case reported in the English literature. We herein describe a similar case affecting two siblings who presented with identical congenital lesions in the same location.

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Introduction

Smooth muscle hamartoma (SMH) is a cutaneous malformation mainly composed of a disorganized proliferation of normal muscle fibers that arise from arrector pili [1]. It usually presents as a single congenital lesion that frequently involves the back and the lower limbs. Unusual clinical presentations, such as atypical localizations, multiple disseminated lesions, and generalized forms have been rarely described [2, 3]. In 2001, Gualandri et al. reported the presence of multiple SMH in three members of the same family, namely two brothers and their mother [4]. This is, as far as we know, the only familial case reported in the English literature. We herein describe a similar case affecting two siblings who presented with identical congenital lesions in the same location.

Case report

Figure 1	Figure 2
Figure 1. Congenital asymptomatic lesions affecting the two siblings. Lesions are more evident on the older girl (left side), who also showed a hairy slightly-hyperpigmented patch in the lumbar area. The boy showed multiple skin-colored papules affecting the lumbosacral area, the buttocks, and both thighs. Figure 2A. Detail of the lesions of the younger brother, which are less obvious. Arrows indicate the presence of small rounded “mother of pearl” papules that tended to coalescence. Figure 2B. Digitate residual lesions on the lumbosacral region (marked with arrows)

An 8-year-old girl and her brother, a 6-year-old boy, were referred to our dermatology department for congenital asymptomatic lesions located on the lower back, the buttocks, and the posterior surface of the thighs (Figure 1). Physical examination of the girl revealed the presence of small rounded skin-colored papules that tended to coalescence, with an area of slight hyperpigmentation and hyperthrichosis in the lumbosacral region. Her brother presented with very similar lesions in almost the same distribution (Figure 2A). Pseudo-Darier sign was evident after rubbing the lesions in both cases.

Curiously, the father also had lesions on the lumbosacral area, of an uncertain evolution time, which presented as digitate plaques with a residual/anetodermic aspect (Figure 2B).

Figure 3
Figure 3. Randomly oriented smooth muscle fibers distributed all over the dermis (H&E, x20)

A biopsy of one papule was performed only in the older child. Parents refused to perform this procedure in her brother. The histopathology showed, under a normal epidermis, the presence of numerous randomly oriented smooth muscle fibers, sometimes in contact with hair follicles (Figure 3). Serial sections of the biopsy revealed the increase of such fibers throughout the entire sample. Neither atypia nor mitotic figures were observed. Desmin and smooth-muscle actin were both positive. Orcein stain did not evidence any alteration. All these findings were consistent with the diagnosis of SMH.

On a subsequent visit, we performed a punch biopsy in one of the father’s lesions. Histopathology (H&E and orcein) only evidenced residual dermal changes without the presence of smooth muscle fibers.

Discussion

Smooth muscle hamartoma can present either congenitally or may be acquired. It remains controversial as to whether acquired lesions are truly hamartomas or merely clinical variants of cutaneous pilar leiomyomas [5].

Congenital SMH usually appears as a single skin-colored or slightly hyperpigmented, irregular patch located on the lumbosacral area, the buttocks, or the lower limbs [6]. It is usually present at birth or shortly thereafter. Other localizations, such as the face, the upper extremities, and the chest have seldom been described [2]. Multiple disseminated lesions have been rarely published [7]. In these cases, different clinical manifestations often coexist (i.e., skin-colored papules that coalesce in “mother of pearl” plaques, hyperpigmented patches or areas of hypertrichosis) [2]. Deep involvement has not been described [6].

Multiple SMH involving different members of the same family has been described only once, in a mother and her two children who had identical lesions in the sacral region and the posterior and lateral surfaces of the thighs [4]. As in our case, the authors biopsied one of the children, which confirmed the diagnosis of SMH. They postulated a hypothetical autosomal dominant transmission, which may explain not only the involvement of different members of the same family but also the same pattern and clinical localization of the lesions.

We here describe a case of two siblings, a girl and a boy with the same lesions in the same localization. Histopathology confirmed the diagnosis of SMH in the girl. The fact that her brother had identical lesions in the same location led us to assume the diagnosis of multiple familial smooth muscle hamartoma. Moreover, their father also presented with anetodermic lesions in the lumbosacral region. Although a punch biopsy did not confirm the diagnosis of SMH, previous reports have described cases of SMH with partial regression [8]. Furthermore, it is well known that clinical manifestations of congenital SMH decrease with age [6]. It is therefore possible that he also suffered from the condition, which would make our case identical to the one reported by Gulandri et al [4]. Hence, as far as we know, this would be the second report of multiple familial SMH. This entity may be underreported because of its benign nature and its subtle clinical presentation.

References

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