Primary Melanoma of the Spinal Cord: A Case Report

Abstract

Primary melanoma is an extremely rare tumour of the spinal cord. We are reporting a case of primary melanoma of the spinal cord in a 55-years-old male patient. Magnetic resonance imaging showed an extradural intraspinal lesion opposite the L4 vertebral body. The lesion was completely resected and a microscopic diagnosis of melanoma was made. Thirty eight months later, the patient is alive, with no evidence of any tumour recurrence. INTRODUCTION CASE REPORTA 55-year-old male patient with a history of back pain, a weakness in the lower extremities and with urinary and anal incontinences, was admitted. His symptoms had progressively worsened to paraplegia. The neurological signs were consistent with lower spinal cord compression. A careful general physical examination did not reveal any lymphadenopathy, organomegaly or cutaneous lesions. A Magnetic Resonance Imaging (MRI) scan revealed an extradural intraspinal lesion opposite the L4 vertebral body, which was widening the intervertebral foramen. A provisional diagnosis of a neurofibroma was made. Intraoperatively, a bluish, engorged, extradural, intraspinal lesion which measured 1 cm was seen to arise in relation to the right L4 root. The lesion was completely resected and it was sent for a histopathological examination. Pathological FindingsGrossly, multiple black friable tissue bits were received. The histological examination showed a spinal cord tissue with a tumour which was composed of proliferating polygonal to spindle shaped cells which had an abundant intra-cytoplasmic brown to black pigment [Table /Fig-1A, B]. The tumour cells had vesicular nuclei with prominent nucleoli [Table /Fig-1C]. The cells were arranged in tight clusters and sheets. Numerous mitotic figures along with an atypical mitosis were found [Table/ Fig-1C]. Bizarre multinucleated giant cells were seen focally. Areas of haemorrhage and necrosis were also present. Masson's Fontana stain for the melanin pigment was positive [Table/ Fig-1D]. A melanin bleach confirmed that the intracytoplasmic pigment was melanin and it highlighted the Pathology Section Ruchi Sinha, TauSeef huSain Rizvi, ShRijeeT chaKRaboRTi, chandRa KumaR ballal, anuP KumaR nuclear features. The Perl's Prussian Blue stain was negative and it excluded the haemosiderin pigment [Table/ Fig-1E]. DISCUSSIONThe present World Health Organiztion classification classifies primary melanocytic lesions of the CNS into diffuse melanocytosis, melanocytoma, meningeal melanomatosis and malignant melanoma. Among these lesions, primary malignant melanoma of the CNS accounts for only 1% of all melanoma cases [1]. The incidence of primary spinal melanoma is even rarer. According to the Hayward classification [3], the diagnosis of primary spinal cord melanoma is based on the absence of a melanoma outside the CNS, the absence of this lesion at any other site in the CNS and a histologic confirmation of melanoma.[ Table/

Primary spinal melanoma of extramedullary origin: a report of three cases and systematic review of the literature

“…The majority of tumors were solitary and only one patient with multiple foci was reported. 4 A few tumors originated from the nerve roots or had spinal nerve root involvement, [5][6][7][8][9] which led to the enlargement of the intervertebral foramen, and even spread outside the intervertebral foramen 2,10 or destruction of the vertebral pedicles. 8,11 Signs and symptoms of this tumor were nonspecific and dependent on location.…”

“…2 Clinically, PSM of extramedullary origin may be misdiagnosed as a neurogenic tumor (schwannoma), ependymoma, metastatic tumor, hematoma or meningioma. 3,[5][6][7][9][10][11][17][18][19] Ninety percent of melanomas found in the CNS are metastatic tumors. 8 A thorough physical examination is required to rule out melanoma in other organs outside of the spinal cord, before a diagnosis of PSM can be established.…”

Thoracic extradural malignant melanoma with unknown primary

“…The survival rate of patients with CNS melanoma is not known exactly, but the prognosis is better than that of patients with cutaneous melanoma. 5 Complete surgical resection is the treatment of choice and radiotherapy is recommended for subtotal resection. 5 Recently, immunomodulation with drugs such as ipilimumab and therapeutics targeting specific mutations such as the BRAF (v-raf murine sarcoma viral oncogene homolog B1) inhibitors vemurafenib and dabrafenib have achieved favourable increases in progression-free survival for patients with metastatic melanoma.…”

Primary Intradural Extramedullary Spinal Melanoma in the Lower Thoracic Spine

“…The radiological method of choice in the diagnosis of spinal cord melanoma is MRI [ 7 ]. Often a lesion in the spinal cord with hyperintensity on native T1-weighted imaging with corresponding hypointense T2 signal is shown.…”