Keys To Diagnosing Metastatic Melanoma In The Foot And Ankle

Christopher Witt, DPM, and Steven Geary, DPM

• Colored lesion
• Uncertain diagnosis
• Bleeding lesions (including chronic granular lesions)
• Enlargement of the lesion despite treatment therapies
• Delay in healing beyond two months.

What The Literature Reveals About Recurrence And Survival Rates

Rates of recurrence vary depending on the literature. In one study, researchers found 36 percent recurrence rates for patients who received local excision and 0 percent for patients treated with digital amputations.4 Overall, they found lesions between 1 to 4 mm had the highest risk of recurrence but after 75 months, lesions greater than 4 mm had a low risk of recurrence. The study authors found no correlation among the histology, thickness and site of origin or mitotic index with recurrence rate. The researchers also found the rate of recurrence with patients with foot melanoma and poor prognostic factors had excellent survival rates in comparison to patients with melanoma of the trunk or extremities.

   Another study found that the five-year overall survival rate for melanoma of the foot and ankle was 63 percent and 51 percent for 10 years.5 In the study, 32 patients with plantar or subungual lesions had a mean duration of survival of 47 months in comparison to 72 months for the 28 patients with foot or ankle lesions. Fifteen patients who had a misdiagnosis had a mean duration of survival of 22 months in comparison to 67 months for 45 patients with correct diagnosis. Another study found that 33 percent of patients with acral lentiginous melanoma of the foot or ankle initially had the wrong diagnosis, and the average time for correct diagnosis was 13.5 months.6

   chronic, intractable pain. The survival rate is also drastically lower. In a study reviewing 11 patients with osseous metastasis of melanoma, researchers found that the mean time from initial diagnosis of melanoma to radiographic evidence of osseous metastasis was 9.75 months.7 After radiographic changes were visible, the mean survival time was 5.67 months. The treatment that one renders at this point is usually supportive at best. The priorities are to prevent fractures and provide pain relief.

What You Should Know About The Patient Presentation

In 2008, a 45-year-old male patient presented to the emergency department after a two-week history of a palpable mass to the right anterior-lateral mid-thigh. Six years earlier, the patient had wide local excision of two suspicious lesions of the back and right calf. The lesion on the back had melanoma and the patient subsequently had an excision of the right axillary lymph nodes. The lesion on the calf later recurred and a second biopsy revealed melanoma as well. The patient reported no further complications until this visit.

   A biopsy of the new lesion on the thigh also revealed melanoma. The patient then went to oncology for treatment including interleukin and radiation therapy.

   The patient then presented to the emergency department for pain to the left anterior ankle and mid-leg in 2010. He denied any trauma to the area. There was no limitation of ankle joint range of motion but there was pain throughout. X-rays, magnetic resonance imaging (MRI), computed tomography (CT) and bone scans found metastases to the left lower leg, clavicle, sternum, liver and brain. X-rays revealed a lytic lesion to the proximal fibula and MRI of the ankle showed an osteochondral lesion of the left talus.

   The patient wore a supportive brace but I lost him to follow-up. After a review of medical records, the patient continued to see oncology for painful lesions that developed in the upper extremities as well as recurrent headaches. The patient received further radiation therapy until his death in 2011.

In Conclusion

Melanoma is the sixth most common cancer in the United States. There will be an estimated 76,250 new cases this year with 9,180 deaths.1 Lesions of the feet and ankle are notoriously misdiagnosed. Without early detection and treatment, survival rates plunge for these patients.

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