An Acrochordon-Like Melanoma Metastasis

Acrochordons are generally assumed to be benign and might not be submitted for pathologic analysis. One study of 1335 clinically diagnosed acrochordons found only 5 malignant tumors.¹ Both squamous cell carcinoma and basal cell carcinoma have been reported in acrochordon-like lesions.^{1 - 2} We report herein a case of acrochordon-like melanoma metastasis.

A 77-year-old white woman was diagnosed as having a melanoma in 1986. Although these medical records were unavailable for review, she self-reported receiving therapeutic excision with primary closure of the left arm and left back sites. Her skin condition remained within normal limits until December 2009, when she developed multiple-pinpoint blue-brown “blood blister ” lesions on her trunk and extremities, which grew in diameter and number over the following 6 months. At this time a skin tag –like lesion of the right hip and blue subcutaneous nodules of the bilateral breasts were biopsied, revealing metastatic melanoma.

At presentation in 2010, the patient pointed out a new lesion of her anterior left axillary vault, which she believed was similar to the initial appearance of the right hip metastasis. The area of concern was a hyperpigmented 2-mm soft, pedunculated papule without surrounding macular erythema or pigmentation that clinically appeared consistent with a benign acrochordon (Figure 1, inset). Dermoscopy revealed a mobile, saccular lesion with globular architecture without discernible vascularity (Figure 1).

Reflectance confocal microscopy (RCM) examination of the epidermis revealed a slightly broadened honeycomb pattern without ulceration or pagetoid cells. The dermoepidermal junction and superficial dermis revealed rare, bright dendritic processes and extensive dense and sparse dermal nests with many large refractile atypical-bizarre cells consistent with melanocytes. Multiple horizontally oriented and convoluted vessels were also noted in close proximity to the tumor nests, consistent with the previously described vascular-tumor interface phenomenon³ (Figure 2A and B) (a video is available).

Histopathologic review demonstrated a well-circumscribed pedunculated lesion with overlying epidermal thinning and effacement of the rete. No ulceration or melanocytic proliferation was noted in the epidermis. Multiple discohesive nests of severely atypical melanocytes were noted in the papillary dermis with closely interposed vessels. The overall picture was consistent with metastatic malignant melanoma (Figure 2C and D).

A positron emission tomography (PET) computed tomography scan demonstrated multiple PET-avid areas; fine needle aspiration confirmed the presence of metastatic melanoma in the left axillary lymph node. The patient started oral temozolomide therapy and was subsequently lost to follow-up.

While it is widely believed that acrochordons are unlikely to be clinically significant and that they may be discarded instead of submitted for pathologic review, cutaneous malignancy may present as an acrochordon mimicker or arise within an existing acrochordon. Patients with Gorlin syndrome (basal cell nevus) may develop acrochordon-like basal cell carcinomas at a fairly young age; invasive squamous cell carcinoma has been reported to develop within an acrochordon; and there is 1 case report of melanoma presenting as an infarcted acrochordon-like lesion.^{4 - 5} While the medical history of the present patient prompted removal of the lesion in question, RCM revealed a concerning architecture that contrasted with the lesion's benign clinical features. Reflectance confocal microscopy may provide additional diagnostic information to help determine appropriate diagnostic options.