Abstract
We present a case of 15-year old male with solitary fibrofolliculoma on the ear and we demonstrate the use of ultrasound in outlining the features of this rare benign skin tumor with histological correlation. Fibrofolliculoma can be associated with a rare syndrome known as Birt–Hogg–Dubé which affects the skin, lungs and kidneys.
Keywords: Fibrofolliculoma, Birt–Hogg–Dubé syndrome, Sonography
Fibrofolliculomas are asymptomatic 2–4 mm lesions that range in color from yellow-white to skin colored. They are smooth and dome-shaped, and appear on the head and neck. Solitary fibrofolliculomas are extremely rare, with only 13 cases published to date. They are non-inherited, present at a younger age, and can present as a large pink pedunculated mass [1]. When multiple fibrofolliculomas are associated with trichofolliculomas and acrochordons, they may be inherited as part of Birt–Hogg–Dubé (BHD) syndrome, which affects the skin, lungs and kidneys and is inherited as autosomal dominant resulting from mutation in the folliculin (FLCN) gene, which encodes the protein FLCN, a tumor suppressor gene [2]. BHD is associated with the formation of pulmonary cysts that may rupture leading to spontaneous pneumothorax, with CT of the chest being the most sensitive modality for diagnosing the cysts. BHD is associated with a 30% risk of renal cell carcinoma (RCC) that increases with age and occurs around the age of 50 years and is mostly bilateral and of the clear cell type on histology. Imaging is the modality of choice for screening for renal cancer, with abdominal MRI being recommended annually starting at the age of 20 [3]. Treatment of solitary fibrofolliculoma consists of surgical excision with histopathological analysis. However, for multiple lesions of fibrofolliculomas, there may be a benefit derived from ablative lasers such as CO2 or erbium-YAG [4].
Here we present a 15-year old male who presents with a painless pink nodule of 1-year duration on his left ear that was initially treated with oral retinoids, with no response. There was no history of trauma or piercing prior to the appearance of the lesion, and no family history or genetic disorders. The patient had picked at the lesion, leading to irritation and some bleeding. Examination of the left earlobe revealed a pedunculated nodule with smooth surface and hemorrhagic crust from bleeding (Fig. 1a). A few acrochordons were noted around the neck area, but otherwise the skin examination and system review were within normal ranges. Sonography of the left ear lesion showed a hypoechoic, well-defined lesion with hyperechoic areas (Fig. 1b) and increased peripheral vascularisation (Fig. 1c). Surgical excision was performed, and histopathology showed a central hair follicle with a proliferation of thin epithelial cords of immature basaloid cells with sebaceous differentiation, surrounded by a fibrotic stroma consistent with fibrofolliculoma (Fig. 1d). Patient had a CT of his chest and abdomen that revealed no abnormal findings.
Fig. 1.
Left ear lobe pedunculated pink nodule (a). Sonography of the lesion showed hypoechoic well-defined lesion with hyperechoic areas (b) and increased peripheral vascularisation (c). Scanning power view showing a central hair follicle with a proliferation of thin epithelial cords of immature basaloid cells with sebaceous differentiation, surrounded by a fibrotic stroma (d)
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Conflict of interest
The author(s) declared no potential conflict of interest with respect to the research, authorship, and/or publication of this article.
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All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
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References
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