Malignant melanoma misdiagnosed as a diabetic foot ulcer

Abstract

Misdiagnosis and delay in diagnosing acral malignant melanoma are quite common and usually associated with a poor prognosis. Non-healing plantar ulcers, including diabetic feet ulcers, are a possible misdiagnosis, with reports of malignant melanoma cases mistaken for diabetic foot ulcers.A 54-year-old male patient, with Type 2 diabetes mellitus, was referred to our department with a painless, non-healing ulcer of 12 months' duration under the right fifth metatarsal bone. The ulcer had been managed for months as a diabetic foot ulcer with local wound care, antibiotics and pressure-relieving footwear. On clinical examination, there was a 2.5-cm diameter ulcer under the right fifth metatarsal head, extending to the fourth interdigital space, with a pigmented macule with irregular borders in the ulcer margins (Fig. 1). An incisional biopsy was taken from the lesion and the histopathological examination showed a malignant melanoma with a Breslow depth of 5.3 mm. Foot amputation was performed and further investigation revealed involvement of the inguinal lymph nodes. The patient died 8 months later with metastatic disease.Malignant melanoma accounts for approximately 4% of all skin cancers, although it causes around 79% of all skin cancer deaths [1]. Acral lentiginous melanoma is the most common melanoma type that presents on the plantar aspect of the foot. The misdiagnosis of acral melanoma is common, occurring in approximately 40% of all cases [2]. Acral melanoma is frequently misdiagnosed because of its less common location and absence of the classical signs of melanoma associated with the mnemonic aid 'ABCD' (asymmetry, border, colour, diameter); moreover, it is frequently ulcerated and amelanotic. Misdiagnosis and delay in diagnosis may lead to poor disease outcome. A retrospective review of plantar melanoma showed that misdiagnosis led to a 12-month mean delay of treatment and was associated with increased tumour thickness (5.0 vs. 1.5 mm) and lower 5-year survival rate (15.4 vs. 68.9%) [2]. In the (a) (b) (d) (c) FIGURE 1 Clinical aspect of the lesion: plantar ulcer under the right fifth metatarsal head, extending to the fourth interdigital space. Histological features of the tumour: (a) and (b) melanoma cells diffusely infiltrating the dermis [haematoxylin and eosin stain (H&E), · 4]; (c) and (d) higher magnification of the melanoma cells (Haematoxylin and eosin stain, · 40).

Acral melanoma with satellitosis, disguised as a longstanding diabetic ulcer: a great mimicry

“…Misdiagnosis is particularly likely in cases of amelanotic melanoma. There are less than 20 melanoma cases misdiagnosed as diabetic foot ulcers in the literature . Most of them are plantar ulcers, mimicking mal perforans .…”

Amelanotic Melanoma Presenting as a Neuropathic Ulcer in a Non-Diabetic Patient

“…The propensity for plantar surfaces along with the amelanotic nature of our patients melanoma were important factors in delaying his referral to a tertiary center. Delayed diagnosis of amelanotic melanoma in the diabetic patient has been well documented but this is the first such case describing a non diabetic patient with a lesion masquerading as neuropathic ulcer [1][2][3]10]. This case highlights the importance of a raised index of clinical suspicion when presented with a non progressing foot ulcer despite appropriate medical management.…”

“…Amelanotic malignant melanoma is a rare form of skin cancer which is commonly misdiagnosed due to its variable presentation and clinical appearance [1][2][3]. This can often lead to a worse prognosis due to delay in management and treatment [4][5][6].…”

The Importance of Wound Biopsy in the Accurate Diagnosis of Acral Malignant Melanoma Presenting as a Foot Ulcer

“…9 This ulceration, combined with atypical features and location of acral melanomas, often results in the subsequent misdiagnosis or delayed diagnosis, and ultimately leads to a poorer prognosis. 19 Therefore, tools for early diagnosis, such as wound biopsy, and determination of extent of malignant spreading are indispensable for early treatment and decreased morbidity and mortality associated with these masqueraded malignancies.…”