Treating A Large Fungating Mass On The Plantar Foot

A 63-year-old African-American male presented with an enlarging hemorrhagic mass on the right foot. The tumor had been present for nearly one year and had continued to increase in size while limiting his normal gait function.

He also had a mass in his right groin that he had noticed approximately four months after the appearance of the foot mass. However, the mass in his groin was causing him no pain or discomfort. In the months prior to presentation, his appetite had diminished and he experienced an unknown amount of weight loss. Finally, the patient was complaining of exertional shortness of breath, which likely was the last straw that encouraged the patient to seek medical attention.

The physical examination revealed a pigmented, malodorous, necrotic, fungating, bleeding 8.9 x 7.1 cm mass that covered much of the lateral plantar surface of the right foot. Bulky right inguinal adenopathy was also present. The discrete large palpable nodes aggregated adjacent to a large ipsilateral palpable tumor mass. The patient would only agree to a core needle biopsy of the lesion, which revealed round epithelioid malignant cells as well as streaming bundles of malignant spindle cells with frequent mitoses and giant nucleoli. The biopsy of the sentinel lymph node showed similar changes. Lab work showed an abnormally high lactate dehydrogenase 1 level (334 mg/dL) and a severe microcytic hypochromic anemia as evidenced by a hemoglobin level of 5.2 g/dL and mean corpuscular volume of 60 fL.

Computerized tomography (CT) scans of the chest, abdomen and pelvis exhibited isolated soft tissue masses within the right groin and right pelvic sidewall, both of which were highly suspicious for a tumor. Furthermore, soft tissue masses in the right anterior cervical triangle, left supraclavicular fossa and the left lung were consistent with metastatic tumor. Magnetic resonance image (MRI) scans of the brain showed a small solitary focus within the left postcentral gyrus, which was suspicious for metastatic tumor. Skeletal metastasis was not evident on bone scan.

However, there was a density, which was suspicious for metastatic tumor at the base of the fifth proximal phalanx adjacent to the fifth metatarsophalangeal joint.

Key Questions To Consider

1. What is your diagnosis of this condition?
2. What are the key characteristics of this condition?
3. What are the positive findings on biopsy?
4. What are the treatment options?

Answering The Key Diagnostic Questions
1. Nodular melanoma of the plantar foot
2. Nodular pigmented lesion with rapid vertical growth and poor prognosis
3. Atypical melanocytes, both single and in nests, with pagetoid spread and ulceration but with sharp lateral circumscription comparable to the dermal invasion depth
4. Wide resection or amputation with or without chemotherapy

What You Should Know About Nodular Melanoma
According to the Centers for Disease Control and Prevention (CDC), skin cancer is the most common cancer in the United States.¹ While skin cancer deaths represent a small percentage of overall cancer deaths, approximately 75 percent of those skin cancer deaths are due to melanoma.² Of the six histologic types of melanoma, the most aggressive is nodular melanoma, first described by Clark and colleagues in 1969.³ This type of melanoma accounts for 10 to 20 percent of all cases. Nodular melanoma cells readily invade, survive and replicate within the dermis.⁴ Regarding melanoma of the lower extremity, pedal neoplasms typically present with higher clinical and histological stages, resulting in poorer prognosis and survival.⁵

While some have suggested that foot trauma and footgear irritation may promote tumor cell spread and aggressive neoplastic activity, a lack of vigilance is most likely the reason for pedal neoplasms presenting at an advanced stage.^6,7 It is noteworthy that in the African-American population, the most common location for melanoma is the plantar surface of the foot.⁸

Essential Diagnostic Insights
Nodular melanoma normally presents as a relatively uniform dark-colored cutaneous nodule, usually with ulceration. In comparison with superficial spreading melanoma, the most common variant, nodular melanoma may not arise from a macular pigmented lesion and has an accelerated vertical growth that facilitates invasion and metastases.⁹

A skin biopsy is vital not only for determining the diagnosis but for determining prognosis. By measuring the extent of invasion and staging the tumor according to Breslow’s depth, we can more accurately determine the severity of the patient’s condition and the likelihood of survival. Indeed, among the cases in the 2008 American Joint Committee on Cancer (AJCC) Melanoma Staging Database, increasing tumor thickness was associated with a statistically significant decrease in five- and 10-year survival rates.¹⁰ Authors broke down the survival rate to include T1 melanomas (≤1.00 mm thickness) with a 92 percent survival rate, T2 melanomas (1.01-2.00 mm) with an 80 percent survival rate, T3 melanomas (2.01-4.00 mm) with a 63 percent survival rate and T4 melanomas (>4.00 mm) with a 50 percent survival rate.

With regard to histology, nodular melanomas and superficial spreading melanoma share many histological features with one main exception: nodular melanomas are more sharply circumscribed laterally than superficial spreading melanomas. While nodular melanomas will still have atypical melanocytes alone or with nests that display pagetoid spread (spread above the basal layer) and ulceration, they will not extend more than three rete ridges lateral to the dermal component. Higher mitotic activity and regression are often present as well with dermal melanocytes assuming a varied histological morphology including spindle-shaped cells, epithelioid cells and balloon cells with abundant pale staining, lipid-laden cytoplasm.¹¹

Physicians have used sentinel node biopsy as the standard evaluation for staging nodal metastases and prognosis. Melanoma tumor metastases can present with intranodal as well as extranodal extension or growth. Extranodal growth in melanoma lymph node metastases is a prognostic factor in predicting disease-free survival prognosis as well as regional recurrence rates.

Additional diagnostic and prognostic factors include metastasis and lactate dehydrogenase levels. We can split patients who present with distant metastasis in skin, subcutaneous tissue or distant lymph nodes into three different categories. The site of metastasis and lactate dehydrogenase levels determines the risk to the patient.¹⁰ Normal lactate dehydrogenase level and metastasis in skin, subcutaneous tissue or distant lymph nodes signify low risk. Normal lactate dehydrogenase level and metastasis to lungs or other location signify intermediate risk. High lactate dehydrogenase and metastases to any other visceral site signify the highest risk.

Pertinent Pearls On Treating Nodular Melanoma
When approaching a patient with neglected metastatic disease, it is important to discuss palliative measures. One must consider local resection versus limb amputation. Histological analysis should guide the physician in determining the depth and extent of surgical excision versus complete amputation. In addition to palliative surgical intervention, curative therapy utilizing interferon and/or high-dose interleukin-2 has been useful. A recent study by Schwartzentruber and coworkers demonstrated significant tumor regression using gp100 peptide vaccine and interleukin-2 with advanced melanoma.¹²

When presented with a patient who has such advanced and diffuse disease, having a multispecialty team is paramount for adequate treatment. Consultation with internal medicine, medical oncology and surgical oncology for complete workup and management is required. Consider referral to a tertiary care facility if the patient arrives at a local community hospital with inadequate resources. The initial workup should include core biopsy or surgical excision. Additionally, consider evaluation for metastasis with brain and chest CT and bone scans.

The patient initially rejected any offer of treatment but ultimately chose a below-knee amputation over a Syme’s amputation due to the lower energy requirement. He also received interferon with high dose interleukin-2 therapy. Despite this, the patient succumbed to his condition within the year while in hospice care. We believe that a psychological illness prevented him from seeking care earlier and from being more cooperative during his treatment.

Dr. Vella is in private practice in Gilbert, Ariz.

The author would like to thank the following people for their contributions to this article: Brent Bernstein, DPM, Steven Hawley, DPM, Zachary Ritter, DPM, Jared Malan, DPM, Emily Miller, MD, Santo Longo, MD, and Stephen Schleicher, MD.

References

1. Centers for Disease Control and Prevention. Skin cancer statistics. Available at https://www.cdc.gov/cancer/skin/statistics . Accessed March 17, 2015.
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12. Schwartzentruber DJ, Lawson DH, Richards JM, et al. Gp100 peptide vaccine and interleukin-2 in patients with advanced melanoma. New Eng J Med. 2011; 364(22):2119-2127.