Fibroepithelioma of Pinkus: poor response to topical photodynamic therapy

ARTICLE

Auteur(s) : Min Young Park, You Chan Kim

Department of Dermatology, Ajou University School of Medicine, 5 Wonchon-Dong, Yeongtong-Gu, Suwon 443-721, South Korea

Fibroepithelioma of Pinkus (FEP) is an uncommon, indolent variant of basal cell carcinoma (BCC) with a distinct growth pattern. For treatment of this tumor, surgical excision has been commonly used. Herein, we attempted treatment with topical methylaminolevulinate (MAL) photodynamic therapy (PDT) for a patient with FEP; however, there was a poor response to this treatment.

A 49-year-old female presented with a 1-year history of skin lesions. Physical examination revealed a 2 cm × 1.5 cm sized brownish, erosive plaque on the right side of the abdomen (figures 1A, B). A skin biopsy specimen from the plaque showed numerous, elongated, anastomosing thin cords of basaloid cells arising from the epidermis. They were embedded in a loose, fibrotic stroma, with some pigmentation and the overall features were consistent with FEP (figure 1C). We explained the treatment options, including surgery and PDT, to the patient. Because she was afraid of surgical procedures and post-surgical scars, we treated the lesion monthly with topical MAL-PDT. The lesion was illuminated with red light from a Waldman PDT 1200 lamp at a light dose of 100 J/cm² and a fluence rate of 100 mW/cm². After five sessions of PDT, the tumor showed regression; however some residual lesion was noted in the skin biopsy. After four more sessions of treatment, the tumor still remained histologically identifiable (figure 1D). Therefore, PDT was discontinued, and a wide surgical excision of the lesion was performed. The patient has been followed for recurrence of disease.

In 1953, FEP was first described by Herman Pinkus, who characterized it as a premalignant fibroepithelial tumor of the skin [1]. Traditionally, FEP is regarded as an unusual variant of BCC. Even though FEP is considered an indolent tumor with a low risk of metastasis, as a variant of BCC, adequate and complete treatment is necessary. Until now, surgical excision has been the most common treatment for FEP. Recently, for the treatment of BCC, there has been an increased use of topical PDT. The use of MAL-PDT has achieved a complete response rate of 85~93% for superficial BCC and 75~82% for nodular BCC at 3 months after the treatments [2].

Therefore, we tried MAL-PDT for FEP in the present case; however nine sessions of treatment demonstrated an incomplete response. The possible reasons for this finding include the following: first, the unique character of the FEP, which is different from classic BCC. Recently, in contrast to the traditional view, FEP has been suggested to be a benign follicular tumor similar to a trichoblastoma [3, 4]. After the application of photosensitizers, neoplastic tissues exhibit a greater preferential production of photoactive porphyrins compared to non-neoplastic cells. Therefore, the benign nature of FEP might be associated with the reduced effectiveness of PDT; second, the character of the stroma of FEP might be associated with the results. It has been shown that morpheic BCC is less responsive to topical PDT than other types of BCC. The abundant fibrous stroma of the tumor has been suggested to interfere with the effects [5]. Even though the amount of fibromyxoid stroma in FEP is less than that of a morpheic BCC, a similar mechanism might be involved in the reduced response of PDT; third, the pigmentation of the tumor could affect the results. It is known that PDT is less effective for pigmented BCCs because the melanin absorbs the photoactivating light required for protoporphyrin IX. Although the pigmentation was very mild in the present case, we can not exclude this possibility of interference [6].

In summary, we report a case of FEP which showed an unsatisfactory response to topical PDT. We suggest that complete surgical excision should be considered as the first line treatment for FEP.

Acknowledgements

References

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