Figure 2. A storiform pattern of fibrohistiocytic cells with intermixedcellular infiltrate, streaks of entrapped collagen, and epidermal hyperplasia.
Figure 3. Closer view of histology.
A 79-year-old man with a history of both and squamous cell carcinoma presents with a slow-growing lesion on the nose, which he notes has been growing for 10 years. On examination, an 8mm pink papule is present on the left nasal alar rim (Figure 1). A shave biopsy is collected. The histologic evaluation reveals a storiform pattern of fibrohistiocytic cells with intermixed cellular infiltrate, streaks of entrapped collagen, and epidermal hyperplasia (Figures 2 and 3).
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Dermatofibroma (DF), also known as a benign fibrous histiocytoma, is a common slow-growing neoplasm of the skin. These growths typically present as a tan-pink to reddish-brown papules or nodules on the lower extremity of adults aged 20 to 50 years.1 Dermoscopy of the lesion classically displays a central white patch and peripheral pigment network.2 Lateral compression or pinching of the lesion often causes central depression, commonly referred to as the dimple sign.3
Histologic evaluation of these lesions characteristically demonstrates a proliferation of spindle cells and histiocytes, often forming a storiform pattern.4 The most common histologic features include a dermal proliferation of spindle cells forming short intersecting fascicles and histiocyte-like cells admixed with multinucleated giant cells, inflammatory cells, and siderophages. Above the dermal proliferation, the epidermis is often hyperplastic with hyperpigmentation of the basal keratinocytes, most commonly over the tips of the elongated rete ridges. At the periphery of the lesion, there is entrapment of collagen. Benign dermatofibromas will stain strongly positive for factor XIIIa and negative for the marker CD34.
Differentiation of dermatofibrosarcoma protuberans from dermatofibroma is accomplished through immunohistochemistry. Dermatofibrosarcoma protuberans samples will stain positive for CD 34 and negative for factor XIIIa, which is opposite to how dermatofibromas will stain.5 Dermatofibrosarcoma protuberans have a more aggressive clinical course and must be treated appropriately.
Dermatofibroma rarely occurs on the face. There are 2 case series found in the literature on the infrequent occurrence of these lesions on the face. One of the series, by Mentzel et al, reported a 0.1% incidence of dermatofibroma occurring on the face in a database of over 33,000 cases.6 The other series demonstrated a 1.1% incidence of DF occurring on the face in a database of 1800 cases of dermatofibroma.7 Dermatofibroma presents even less often on the nose with only 7 prior cases of dermatofibroma on the nose found in the literature.6-8 Because of this reason, dermatofibroma of the nose is not often suspected clinically. The proposed differential diagnosis often includes basal cell carcinoma, melanocytic nevi, adnexal neoplasms, or fibrous papules.9
Typically, dermatofibromas can be identified clinically and, unless bothersome or symptomatic, patients can be reassured on their banal nature with no further therapy indicated. However, Mentzel et al have suggested that dermatofibromas of the face are more aggressive than those that occur in more typical locations. In their case series of 34 dermatofibromas of the face, invasion was seen into deep tissue and muscle in 50% of cases with a recurrence rate of 18.5%.6 Dermatofibromas occurring in more typical locations, such as the lower extremities, have a recurrence rate of 1% to 2% despite often incomplete excision.4 Mentzel et al, therefore, suggested surgeons should take wider margins for the excision of dermatofibromas on the face.6 More recently, a case series of 20 patients with dermatofibromas on the face reported few instances of deep invasion and no recurrences after marginal excision.7 The best treatment approach for dermatofibromas of the face remains inconclusive and debated.6,7
In the case presented, the fibrohistiocytic cells stained positive for factor XIIIa and negative for S-100 and CD34. After shave biopsy, no further treatment was pursued. At 7 months after biopsy, the patient reports no recurrence or growth in the area.
Caroline Gerhardt, BS, is a medical student at the University of South Florida Morsani College of Medicine in Tampa; David Aung-Din, MD, works in the Department of Dermatology, University of South Florida Morsani College of Medicine; Leslie Turner, MD and Katherina Basic, MD, work in the Department of Dermatology, James A. Haley Veterans’ Hospitals in Tampa.
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2. Kelati A, Aqil N, Baybay H, Gallouj S, Mernissi FZ. Beyond classic dermoscopic patterns of dermatofibromas: a prospective research study. J Med Case Rep. 2017;11(1):266. doi:10.1186/s13256-017-1429-6
3. Fitzpatrick TB, Gilchrest BA. Dimple sign to differentiate benign from malignant pigmented cutaneous lesions. N Engl J Med. 1977;296(26):1518. doi:10.1056/NEJM197706302962610
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5. West KL, Cardona DM, Su Z, Puri PK. Immunohistochemical markers in fibrohistiocytic lesions: factor XIIIa, CD34, S-100 and p75. Am J Dermatopathol. 2014;36(5):414-419. doi:10.1097/DAD.0b013e3182a70396
6. Mentzel T, Kutzner H, Rütten A, Hügel H. Benign fibrous histiocytoma (dermatofibroma) of the face: clinicopathologic and immunohistochemical study of 34 cases associated with an aggressive clinical course. Am J Dermatopathol. 2001;23(5):419-426. doi:10.1097/00000372-200110000-00006
7. Estela JR, Rico MT, Pérez A, et al. Dermatofibroma of the face: a clinicopathologic study of 20 cases. Actas Dermosifiliogr. 2014;105(2):172-177. doi:10.1016/j.ad.2013.10.002
8. Singh S, Patra S, Bhari N. Dermatofibroma over the face. Indian Dermatol Online J. 2019;10(1):94-95.
9. Sand M, Sand D, Thrandorf C, Paech V, Altmeyer P, Bechara FG. Cutaneous lesions of the nose. Head Face Med. 2010;6:7. doi:10.1186/1746-160X-6-7