Clinical Misdiagnosis of Steatocystoma Simplex of Eyebrow in a Pediatric Patient.

To the Editor: A 4-year-old girl presented with a 16-month history of swelling of the eyebrow. Pediatricians and general surgeons diagnosed her with sebaceous cyst, and because of unsuccessful treatment with two surgical drainages and antibiotic therapy, she was referred to our unit. On examination, a soft, freely movable, nontender subcutaneous lesion was noted on the left eyebrow [Figure 1]. Other findings of the examination were unremarkable, and there was no family history of similar lesions. Upon our presumptive diagnosis of dermoid cyst, we excised it, and the intraoperative view revealed a soft mobile cystic lesion with a fibrous-like wall filled with oily yellow fluid without surrounding soft-tissue invasion. Findings of histopathological examination were compatible with steatocystoma [Figure 1], so she was diagnosed with steatocystoma simplex. At the 5-year follow-up, there were no signs of recurrence or development of other cutaneous cystic lesions.

Figure 1

Frontal and basal photographs showing a nodular lesion of the left eyebrow with normal overlying skin (left); photomicrograph of surgical specimen showing squamous epithelium lining the cyst wall with scattered sebaceous glands consistent with steatocystoma simplex (right) (H and E, original magnification, ×80).

Steatocystoma simplex, an extremely rare benign nevoid malformation of the pilosebaceous duct junction zone, is the solitary counterpart to the histopathologically identical inherited condition of steatocystoma multiplex.[1] It was initially considered an adult condition.[1] However, according to a comprehensive English literature review (Medline and Embase databases) performed in July 2015, without date restriction by searching the term “steatocystoma” combined with the terms “child”, “infant”, “pediatric”, and other related terms, to the best of our knowledge, only two cases of pediatric facial steatocystoma simplex have been described to date,[2] suggesting that this condition also arises congenitally.[2] We reported a child with steatocystoma simplex misdiagnosed and undertreated as sebaceous cyst by pediatricians and general surgeons and misdiagnosed as dermoid cyst by us. In the literature, cases of steatocystoma simplex misdiagnosed as sebaceous cyst, dermoid cyst, epidermal cyst, chalazion, and lipoma have been reported.[234] Misdiagnosis was probably due to the rarity of the condition and secondary to unawareness by physicians and insufficient clinical information such as absence of thoughtful history-taking and physical examination. The limited space allocated to steatocystoma simplex in standard textbooks compared to other cutaneous cysts may partially explain the lack the knowledge. In addition, with the rapid extension and available advanced imaging techniques and laboratory tests, there is a tendency for some physicians to rely more on technology reports for diagnosis rather than history, physical findings, and the clinical judgment. It is relevant in different clinical settings, including this case, because there were no specific clinical, laboratory, and/or radiologic diagnostic criteria that aided in diagnosing steatocystoma simplex.[234] Although magnetic resonance imaging can be useful in excluding epidermoid cysts and dermoid cysts,[2] further diagnostic imaging has not been indicated before treatment of an isolated facial cutaneous cystic lesion.[5] Physicians should, therefore, be aware of the possibility of steatocystoma simplex mimicking common cutaneous cystic lesions and consider it in the differential diagnoses when evaluating any pediatric patient with facial cystic lesions.[25] Complete surgical excision of steatocystoma simplex is both diagnostic (sebaceous gland attached to the cystic wall is a histopathological pathognomonic feature) and therapeutic (surgical removal of the cyst wall intact is curative and prevents recurrence).[1234]

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