Atypical Fibroxanthoma Treated with a Topical Combination of Imiquimod, Tazarotene, and 5-Fluorouracil

Abstract

This case report describes an 80-year-old man who presented with a growing erythematous nodule with erosion, measuring 0.6 cm × 0.6 cm, on his right temple. This lesion was later diagnosed as atypical fibroxanthoma (AFX). Instead of undergoing Mohs surgery, the gold standard treatment, the patient opted to pursue a topical treatment regimen because of financial costs associated with surgical removal and repair. This topical regimen consisted of tazarotene cream, imiquimod cream, and 5-fluorouracil solution, applied for 30 days. The patient was directed to use this combination 5 days per week for 6 weeks. The specified dosage for each medication was a fifth of a packet of imiquimod 5% cream, an equivalent amount of tazarotene 0.1% cream, and a single drop of 5-fluorouracil 2% solution. These were combined on a bandage and placed on the lesion overnight. Following the treatment, a 3-week post-application examination revealed an erosion, 1.0 cm × 0.9 cm, amidst erythema. A subsequent incisional biopsy with histopathology and stains for CD10 and CD99, 3 weeks after treatment, and three punch biopsies with histopathology and stains for CD10 and CD99, 1-year post-treatment, confirmed the absence of AFX. AFX is a superficial variant of pleomorphic dermal sarcoma (PDS), which shares histologic similarities, yet the exact relationship between AFX/PDS and undifferentiated pleomorphic sarcoma is still not well understood. Previous studies have indicated a genomic similarity between AFX/PDS and cutaneous squamous cell carcinoma (cSCC), which suggests the potential efficacy of cSCC-targeted treatments for AFX/PDS. This case marks the first recorded instance of successful topical medical treatment of AFX, offering an alternative for patients who may opt out of surgical intervention. Continued research to assess the broader efficacy of this approach is encouraged.

Keywords: 5-fluorouracil; Atypical fibroxanthoma; Imiquimod; Nonsurgical; Tazarotene; Topical therapy.

Fig. 1

AFX on the right temple. Arrow highlights an area that is focally eroded

Fig. 2

a Hematoxylin and eosin stain of AFX before treatment. There is a dermal neoplasm, which is composed of spindle-shaped cells beneath an eroded epidermis. b Hematoxylin and eosin stain of the area after topical treatment showing an inflamed but otherwise essentially normal dermis (absent for AFX). The epidermis is broadly absent, and there is an acutely inflamed crust. c Immunostain for CD10 of the pretreated AFX. d Immunostain for CD10 of the area after treatment. e Immunostain for CD99 of the pretreated AFX. f Immunostain for CD99 of the area after topical treatment. (a–f, ×40)

Fig. 3

Site of previous AFX on the right temple, 3 weeks after last topical application of combination therapy. There is an ulceration in a background of erythema. After this picture was taken, a deep incisional second biopsy was performed to determine if there was complete treatment of the AFX

Fig. 4

Final appearance on the right temple at 1-year follow-up that was previously treated with a combination of tazarotene, 5-fluorouracil, and imiquimod. There was acceptable cosmesis with erythema and minimal scarring