Nevus Sebaceous at an Unusual Location: A Rare Presentation.

To the Editor: Nevus sebaceous (NS) is an epidermal nevus that is comprised predominantly of sebaceous glands in approximately 0.3% of newborns.[1] Clinically, it presents as a single or, less commonly, multiple yellowish-colored plaques with overlying alopecia, usually confined on the scalp; however, it can also appear on the face, preauricular area, and neck region.[23] Here, we reported a case of NS in a discrete linear pattern located on the left chest region, in contrast with typical cases, to assist physicians in the early diagnosis of this condition and to prevent unnecessary examinations and inadequate therapeutic interventions.

A 38-year-old female presented with a few localized, yellowish, and slightly verrucous growth lesions on her left chest for more than 20 years [Figure 1a]. The lesions were nonprogressive, both in size and extent, except for proportional increase with body size. The patient wanted to have the lesions removed for cosmetic reasons. Cutaneous examination showed that the lesions were several separate purples and small plaques arranged in a discrete linear pattern on her left chest. They were round or irregularly shaped with clear boundaries with normal skin and size of 0.5–1.5 cm. Moreover, lesions were soft on palpation and did not exhibit any subjective. The patient had no associated systemic abnormalities, such as seizures, vision or hearing impairment, or skeletal deformities, except for the abovementioned lesions. Laboratory tests, including routine hematological examination, liver and renal function tests, and serum lipids and sugar level, were all normal. Chest and skull radiographs and abdominal ultrasonography revealed no abnormalities. Biopsy was taken from the bottom of the lesion, and histological examination revealed a large number of mature sebaceous glands, slight papillomatosis with hyperkeratosis, and acanthosis of the epidermis [Figure 1b]. In the dermis, parts of sebaceous glands were connected to the overlying epidermis [Figure 1c]. A final diagnosis of NS was made based on the clinical and histopathological findings. The purples and small plaques were cut off, respectively, with the least scar (cosmetic reasons) and did not recur 5 months after the surgery.

Figure 1

Clinical and histopathological findings of a 38-year-old female with nevus sebaceous. (a) Clinical examination demonstrated several separate purples and small plaques arranged in a discrete linear pattern on her left chest. They were round or irregularly shaped with circumscribed boundaries with normal skin and size of 0.5–1.5 cm. (b) Histopathological findings showed a large numbers of mature sebaceous glands, slight papillomatosis with hyperkeratosis, and acanthosis of the epidermis (H&E staining, ×40). (c) In the dermis, parts of sebaceous glands were connected to the overlying epidermis (H&E staining, ×100).

NS is a type of organoid nevus. Classically, it presents at infancy as a single bald patch over the scalp and generally remains unchanged until puberty after which the patch becomes more thickened and protuberant and at times verrucous or nodular, with a smooth velvety surface.[1] Among 202 cases of Chi et al.,[2] the most common site of NS was the scalp (66.8%), followed by the face (26.7%) and the neck (5.5%). However, NS may also be present at other sites, such as the trunk or mucosae,[345] or have an atypical morphology. In a case, NS was located on the back as a part of an extensive NS with velvety appearance.[1] However, in our case, the patient presented a rare morphological variant of NS with discrete linear growth appearance on the chest (a morphology of several separate purples and small plaques), which was different from the classic presentation. NS that can be associated with other syndromic features such as mental retardation, central nervous system abnormalities, oculocardiac defects, or skeletal abnormalities is called linear NS syndrome, or Schimmelpenning syndrome (a neurocutaneous phakomatosis).[6] In this case, no involvement of oral and genital mucosae was seen. No multisystem disorders, such as neurological, ophthalmological, and skeletal abnormalities, were associated with the linear sebaceous nevus syndrome.

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