A case of malignant melanoma after repeated recurrent dysplastic nevi

Abstract

Dysplastic nevus is common and affects about 10% of the northern European-descendent population. Studies over the past several decades have identified dysplastic nevi as a risk factor for malignant melanoma. Furthermore, in rare cases, they confirmed that dysplastic nevi have progressed to melanoma. Cases in which dysplastic nevi progressed to malignant melanoma in multiple studies are not uncommon. A 35-year-old woman presented with the major symptom of multiple itchy brown nodules (2.0 cm× 1.3 cm) in the left cheek that had first appeared 20 years earlier. Complete excision was performed at the first visit; subsequent biopsy confirmed that they were dysplastic nevi. They recurred three times over 3 years at the same site, all of which were histologically diagnosed as dysplastic nevi. Five years after the final excision, a brownish nodule developed in the left cheek, with others at the left temporal region, right retroauricular region, and left shoulder at the same time. These lesions were histologically diagnosed as malignant melanoma. We experienced a case of malignant melanoma that occurred at the same site after three recurrences of dysplastic nevi. Although rare, the possibility of malignant melanoma should be considered in follow-ups in cases involving repeatedly recurrent dysplastic nevi.

Keywords: Dysplastic nevus syndrome; Melanoma; Recurrence.

Fig. 1.

Multiple itchy brownish nodules. Multiple itchy brownish nodules (2.0 cm×1.3 cm) in the left cheek that had first appeared 20 years prior.

Fig. 2.

First recurrence. A 0.5 cm×0.5 cm nodule that developed 15 months after the first excision.

Fig. 3.

Second recurrence. A 1.0 cm×0.5 cm nodule that developed 10 months after the second excision.

Fig. 4.

Third recurrence. A 0.5 cm nodule that developed 9 months after the third excision.

Fig. 5.

Histopathologic findings of recurrent dysplastic nevus (third recurrence). Melanocytes: round, regular cells with moderate amounts of cytoplasm. No nuclear atypia, pleiomorphism, or mitosis are visible (H&E, ×400).

Fig. 6.

Mass after three times of recurrence of dysplastic nevi. Mass in the left shoulder, left cheek, and right retroauricular region that developed 5 years and 9 months after the fourth excision, respectively. (A) Left cheek and (B) left shoulder.

Fig. 7.

Histopathologic findings of malignant melanoma after repeated recurrent dysplastic nevi. Tumor cell: round to oval nuclei showing mild nuclear pleomorphism with small nucleoli and irregular nuclear membrane. The cytoplasm contains melanin pigmentation. No mitosis is evident (H&E, ×400).