DermDx: Brown Spot on Back

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A 60-year-old woman presents for a full-body skin examination as she is concerned about several dark spots on her face and chest. She admits to ample sun exposure and denies prior history of skin cancer. She is currently on medications for control of hypertension and hypercholesterolemia. Examination reveals scattered lentigines and seborrheic keratoses. A 1.5-cm hyperpigmented nodule is noted on her back. When questioned about the lesion, she denies antecedent trauma to the area and was uncertain as to when the lesion first appeared. Palpation elicits slight tenderness. A punch biopsy is performed.

Dermatofibromas are commonly encountered neoplasms that occur most frequently on the extremities. Dermatofibromas are most commonly seen in women aged 45 to 64 years.1 Lesions may be the result of a localized reaction to external trauma, such as an insect...

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Dermatofibromas are commonly encountered neoplasms that occur most frequently on the extremities. Dermatofibromas are most commonly seen in women aged 45 to 64 years.1 Lesions may be the result of a localized reaction to external trauma, such as an insect bite or minor abrasion, and pathogenesis appears to involve interaction between fibroblasts, keratinocytes, and mesenchymal cells.2

Dermatofibromas are slow-growing lesions and usually asymptomatic although tenderness may be elicited with pressure. Lateral compression often induces a dimple-like depression. Coloration varies from a light brown to a reddish hue. Eruptive dermatofibromas may arise during pregnancy or as a consequence of immunosuppression and infection with HIV.3

A number of histopathologic variants have been reported; the majority are termed fibrous histiocytomas. These present as noncapsulated, ill-defined dermal lesions that can extend into superficial adipose tissue. Interlacing fascicles of spindled cells are surrounded by a loose collagenous stroma containing fibroblasts, macrophages, and blood vessels.4 Several distinct patterns have been identified with dermoscopy and this tool may aid in clinical diagnosis.5

Dermatofibromas are benign and excision with narrow margins is curative.

Greg Forsyth, PA-C, is a physician assistant at the DermDox Dermatology Centers in Camp Hill and Mechanicsburg, Pennsylvania. Stephen Schleicher, MD, is director of the DermDox Center for Dermatology in Pennsylvania, associate professor of medicine at Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.

References

1.  Han TY, Chang HS, Lee JH, Lee WM, Son SJ. A clinical and histopathological study of 122 cases of dermatofibroma (benign fibrous histiocytoma). Ann Dermatol. 2011;23(2):185-192. doi:10.5021/ad.2011.23.2.185

2. Yamamoto T. Dermatofibroma: a possible model of local fibrosis with epithelial/mesenchymal cell interaction. J Eur Acad Dermatol Venereol. 2009;23(4):371-375. doi:10.1111/j.1468-3083.2009.03089.x

3. Zaccaria E, Rebora A, Rongioletti F. Multiple eruptive dermatofibromas and immunossupression: report of two cases and review of the literature. Int J Dermatol. 2008;47:723-727. doi:10.1111/j.1365-4632.2008.03575.x

4. Alves JVP, Matos DM, Barreiros HF. Variants of dermatofibroma—a histopathological study. An Bras Dermatol. 2014;89(3):472-477. doi:10.1590/abd1806-4841.20142629

5.  Zaballos P, Puig S, Llambrich A, Malvehy J. Dermoscopy of dermatofibromas: a prospective morphological study of 412 cases. Arch Dermatol. 2008;144:75-83. doi:10.1001/archdermatol.2007.8

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