Dear Editor:
A 21-year-old male presented with several, asymptomatic brownish verrucous mass and plaques on the volar side of the left index and middle fingers, which lasted for two years (Fig. 1). He had a history of autologous skin graft from the thigh for burn injury on the same site 10 years ago. Histopathological examination showed prominent acanthosis with hyperkeratosis and verrucous papillomatosis (Fig. 2). Human papillomavirus (HPV) immunohistochemical staining performed to differentiate palmar warts was negative. With the clinical and histopathological findings, we diagnosed him with seborrheic keratosis.
Fig. 1. Brownish verrucous mass and plaques in a 21-year-old male. We received the patient’s consent form about publishing all photographic materials.
Fig. 2. (A) Photomicrograph from the left index finger (H&E, ×40). (B) Acanthosis with hyperkeratosis and verrucous papillomatosis (H&E, ×100).
Seborrheic keratosis is the most common acquired benign epithelial tumor, often wart-like lesion. It can be found on any area of the skin, with the exception of the palms and soles1.
The exact etiology of seborrheic keratosis is unknown. Genetic propensity, sun exposure, HPV has been thought to be involved in pathogenesis. Also, growth factors including transforming growth factor-α, epidermal growth factor, insulin-like growth factor derived from tumor cells and the wound healing process are associated with it2,3.
In the process of wound healing, various growth factors and cytokines are secreted via platelets and macrophages, and they stimulate epidermal and dermal repair4. Satterfield and Haas3 described a patient with seborrheic keratoses associated with a graft site postoperatively. Choi et al.2 reported a case of seborrheic keratosis occurring at the operation site and suggested that growth factors induced by wound healing make a seborrheic keratosis on the operation site.
For our case, the fact that grafted skin is from the thigh where seborrheic keratosis usually occurs can be one possible explanation. Also, growth factors induced in a wound healing process would have contributed to it. To the best of our knowledge, this is the first reported case of seborrheic keratosis occurring on the palm.
Footnotes
CONFLICTS OF INTEREST: The authors have nothing to disclose.
FUNDING SOURCE: None.
References
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