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Folliculosebaceous cystic hamartoma with hair shaft fragments

European Journal of Dermatology. Volume 15, Number 2, 105-6, March-April 2005, Clinical report

Summary

Author(s) : Kenji Yamagata, Tsuyoshi Mitsuishi, Seiji Kawana , Department of Dermatology, Nippon Medical School, 1-1-5, Sendagi, Bunkyou-ku, Tokyo, 113-8603, Japan.

Summary : We describe herein a 57-year-old Japanese male with a folliculosebaceous cystic hamartoma (FCH) presenting several hair shaft fragments in the cyst. Clinically, a skin-colored, dome-shaped, hard nodule, 5 × 4 mm in diameter was observed on the antitragus of his left ear. Histological examination revealed a large cystic structure surrounded by multiple mature sebaceous lobules and rudimentary hair follicules in the middle of the dermis. The cystic structure contained laminated orthokeratotic keratin and several hair shaft fragments. The fibrous stroma invaded the sebaceous lobules and obvious clefts were seen around the folliculosebaceous units located in the dermis. These features are characteristic histological findings of FCH. To our knowledge, this case is unusual with the presence of hair shaft fragments within the cystic structure. In addition, we discuss the histopathological findings of FCH and also review other cases of FCH in the literature.

Keywords : ear, folliculosebaceous cystic hamartoma, hair shaft fragments, sebaceous trichofolliculoma

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ARTICLE

Auteur(s) :, Kenji Yamagata, Tsuyoshi Mitsuishi^*, Seiji Kawana

Department of Dermatology, Nippon Medical School, 1-1-5, Sendagi, Bunkyou-ku, Tokyo, 113-8603, Japan

accepté le 28 Juin 2004

Folliculosebaceous cystic hamartoma (FCH) is a rare cutaneous hamartoma comprised of follicular, sebaceous and mesenchymal elements. FCH was first described in 1991 by Kimura et al. [1]. FCH usually occurs on the central part of the face, especially on the nose [1]. Histopathologically, FCH can be distinguished from sebaceous trichofolliculoma based on its characteristic structures. In this report, we describe a further variant case of FCH with hair shaft fragments of the cyst presenting on the left ear in a 57-year-old Japanese male.

Case report

A 57-year-old Japanese male was referred to our hospital for an asymptomatic skin lesion on his left ear. He had noticed the lesion one year previously. On clinical examination, a skin-colored, dome-shaped, hard nodule was found on the antitragus of his left ear ( (figure 1) ). The lesion was surgically removed under local anesthesia. Histological examination revealed a large infundibular cystic structure lined by stratified squamous epithelium in the middle of the dermis. The epidermis was almost intact and was not attached to the cystic structure. The cystlike structure contained laminated orthokeratotic keratin and several hair shaft fragments. Numerous mature sebaceous lobules were attached to this cyst-like structure though sebaceous ducts and rudimentary hair follicles were also present in its wall. This folliculosebaceous unit was surrounded by dense fibrillary bundles of collagen in concert with numerous capillaries and venules, and was separated from them by prominent clefts ( (figure 2 )A,B).

Discussion

Folliculosebaceous cystic hamartoma (FCH) is a distinct type of cutaneous hamartoma which is formed from stromal and epithelial elements. The histological criteria of FCH as proposed by Kimura et al. [1] were described in 1991. Our case conforms to the distinct histological criteria of FCH. To date, 24 cases of FCH have been reported. Although genital and multiple lesions occasionally occur [2], most of the cases have been located on the face as a solitary lesion [1]. Nine of 24 (37.5%) of those cases were found on the nose, while only 2 cases (8.3%) were found on the ear [3]. The duration of the lesion varied from 1 year to 24 years. They ranged in size from 0.4 × 0.4 to 7.0 × 4.5 cm. The histological differential diagnosis includes sebaceous trichofolliculoma (STF). STF is also an adnexal tumor which is considered to be a variant of trichofolliculoma [4]. Histologically, STF mimics FCH closely, because STF exhibits a large central, epithelial-lined cavity or sinus, radiating numerous sebaceous follicles. The differences between FCH and STF are as follows; in STF, widely dilated sinus tracts communicate directly with the surface epithelium, and no obvious mesenchymal changes are seen as they are certainly seen in FCH [1]. As a rare feature of FCH, some histological variants have appeared in some reports, e.g., the existence of stromal alterations and/or epithelial differentiation [5, 6]. Our case is of interest from two points of view compared with other cases. Firstly, the histological features of our case are typical but present with hair shaft fragments within the cystic structure. Our case is considered as a rare variant of FCH which developed to hair follicle differentiation. Secondly, the location of the lesion seems to be exceptional.

References

1 Kimura T, Miyazaki H, Aoyagi T, Ackermann AB. Folliculosebaceous cystic hamartoma: A distinctive malformation of the skin. Am J Dermatopathol 1991; 13: 213-20.

2 Bologina JL, Longley. Genital variant of folliculosebaceous cystic hamartoma. Dermatology 1998; 197: 258-60.

3 Toritsugi M, Yamamoto T, Nishioka K. Folliculosebaceous cystic hamartoma. Pract Dermatol 2002: 281-4; (in Japanese).

4 Plewig G. Sebaceous trichofolliculoma. J Cutan Pathol 1980; 7: 394-403.

5 Fogt F, Tahan SR. Cutaneous hamartoma of adnexal and mesenchyme: A variant of folliculosebaceous cystic hamartoma with vascular-mesenchymal over growth. Am J Dermatopathol 1993; 15: 73-6.

6 Donati P, Balus L. Folliculosebaceous cystic hamartoma: reported case with a neural component. Am J Dermatopathol 1993; 15: 277-9.