Adachi, Koji

Goto, Hiroyuki

Yamamoto, Osamu

Yoshida, Yuichi

Yonago Acta Medica

Tottori University Research Result Repository

59Yonago Acta medica 2014;57:59–60 Patient ReportEpidermal Cyst with Ossification: A Patient ReportHiroyuki Goto, Koji Adachi, Yuichi Yoshida and Osamu YamamotoDivision of Dermatology, Department of Medicine of Sensory and Motor Organs, School of Medicine, Tottori University Faculty of Medicine, Yonago 683-8504, JapanABSTRACTEpidermal cysts are common skin tumors that are com-posed of a cyst wall of epidermal cells and central keratin material. They rarely show ossification. A 68-year-old man was referred to our clinic for evaluation of multiple cysts on his left forehead, left cheek and right shoulder. Histopathological examination revealed that all of the cysts were epidermal cysts, and focal ossification was observed outside the cyst on the forehead. We speculated that chronic inflammation caused ossification around the cyst. Therefore, epidermal cyst should be included in the differential diagnosis of cysts with ossification.  Key words    epidermal cyst; ossification; trichilemmal cyst  Epidermal cysts are common skin tumors that are com-posed of a keratinocytic cyst wall and central keratin material.1 They usually occur in an area with abundant pilosebaceous follicles. Epidermal cysts rarely show os-sification unlike other cysts such as trichilemmal cysts. Here we present an unusual case of an epidermal cyst with ossification. Corresponding author: Hiroyuki Goto, MDh.gotou.19850820@gmail.comReceived 2013 December 24Accepted 2014 January 8 the forehead showed focal ossification outside the cyst (Fig. 2).DISCUSSIONEpidermal cysts are common tumors that are composed of a cyst wall and keratin material. It is sometimes dif-ficult to distinguish epidermal cysts from trichilemmal cysts only from clinical features. An epidermal cyst has keratohyaline granules in the cyst wall, but a trichilem-mal cyst does not have such granules. In our case, kera-tohyaline granules were seen in the cyst wall. Fig. 1. Clinical feature: the tumor on the forehead. Fig. 2. Histopathological examination: the arrow shows the area of ossification area outside the cyst (hematoxylin and eosin). Bar = 500 μm.PATIENT REPORTA 68-year-old man was referred to our clinic for evaluation of multiple cysts on his left forehead, right shoulder and right back. He had a more than 10-year history of the lesions. The sizes of the tumors were 15 mm on the fore-head (Fig. 1), 20 mm on the cheek and 77 mm on the shoulder. He had a past history of inflammation around the tumors. The cysts were excised under general anesthesia. Each of the cysts was composed of a mass of epithelial cells containing keratinous material. Based on results of histopathological examination, a diagnosis of epider-mal cysts was made. The tumor on 60H. Goto et al. About one quarter of trichilemmal cysts show focal calcification.1 It has been reported that idiopathic calci-nosis of the scrotum is associated with epidermal cyst.2 However, it is rare for epidermal cysts to be accompa-nied by ossification. There is only one such case report in the published literature.3 That case was in the testis with ossification inside the cyst. On the other hand, our case patient showed ossification outside the cyst. Satoh et al. reported that ossification might be caused by degeneration of keratin material.3 We specu-late that chronic inflammation caused by repeated rup-ture of the cyst resulted in the ossification. When we excised the cyst, we found that it had strongly adhered to surrounding tissue, suggesting the presence of chronic inflammation. In our case, when the cyst ruptured, kera-tin material would have been scattered outside the cyst, leading to ossification around the cyst wall.  It is very rare for an epidermal cyst to show ossifica-tion, but epidermal cysts should be included in differen-tial diagnosis of cysts with ossification.The authors declare no conflict of interest.REfERENCES1 Weedon D. Weedon’s skin pathology. 3rd edition. London: Churchill Livingstone; 2010. p. 442-3.2  Saad AG, Zaatari GS. Scrotal calcinosis: is it idiopathic? Urol-ogy. 2001;57:365. PMID: 11182365.3  Satoh S, Yamamoto T, Aoki H, Fuzizuka I, Kubo T, Ohhori T, et al. [Epidermoid cyst of the testis: a report of 2 cases.] Hinyokika Kiyo. 1988;34:1265-8. Japanese. PMID: 3051954.

Epidermal cyst with ossification : a patient report

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Epidermal cyst with ossification : a patient report

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