Case Presentation
An otherwise healthy 35-year-old male presented with a tender and fast-growing nodule on the flank, of one year of evolution. Clinical examination showed a 2 cm firm and shiny pigmented nodule. Dermoscopy revealed brown radial lines and perifollicular scaling, together with coiled and twisted hairs. Structureless pale areas were also observed (Figure 1). Histologic evaluation confirmed the diagnosis of a benign form of a granular cell tumor (GCT).
Figure 1.
Dermoscopic image showing a pigmented tumor with large, radial brown lines. Perifollicular scaling, together with coiled and twisted hairs is also observed, as well as structureless pale areas.
Teaching Point
GCT is an infrequent tumor usually presenting as a firm, sometimes pigmented nodule on mucosae or on the skin of the head or neck. GCT seems to originate from Schwann cells, which is supported by the expression of S-100 and myelin proteins upon immunohistochemical staining. Dermal collagen, small nerves and adnexal structures are commonly infiltrated by tumoral cells, even though only 1%–2% of GCT are malignant. Surgical excision is the recommended treatment. Very few dermoscopic reports are found in the literature. Dermoscopy of GCT can show a yellowish center (with or without hypopigmented lines), surrounded by thin brown reticular lines. Small pale circles have also been described [1,2]. Differential diagnosis of tumors presenting with brown reticular lines is broad and includes melanocytic and non-melanocytic lesions such as dermatofibroma, seborrheic keratosis, solar lentigo, cutaneous mastocytosis, supernumerary accessory nipple and syringoma [1]. We present new dermoscopic features of GCT: large, radial brown lines, and the presence of follicular involvement.
Differential diagnosis of pigmented lesions can be challenging. Dermoscopy may help to confirm suspected GCT.
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Footnotes
Funding: None.
Competing Interests: None.
Authorship: All authors have contributed significantly to this publication.
References
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