Abstract
Primary intraparenchymal brain melanocytic lesions are very rare and arise from leptomeninges in the superficial cortex with invariably poor clinical outcome. We report a case of a 45-year old male who presented with an intraparenchymal brain lesion without meningeal involvement, radiologicallly consistent with primary brain tumor. However, the pathology of excisional biopsy proved to be melanoma on histopathology and immunohistochemistry. Treatment consisted of limited surgery followed by local radiotherapy with the patient had no significant clinical improvement, and was managed conservatively with steroids along with chemotherapy. The patient died due to diffuse intracranial dissemination within 4 months from completion of radiotherapy.
Keywords: Primary brain melanoma, intraparenchymal
INTRODUCTION
Primary intracranial melanomas are relatively uncommon (2-10%) [1, 2] and are usually diagnosed as gliomas which are more common with similar presentation. The differentiation is commonly made after histopathology and Immunohistochemistry [2]. These patients have a short overall survival time despite optimal local and systemic treatment approaches.
Here we report an unusual case of a 45 year male with intraparenchymal brain melanoma without meningeal involvement.
CASE REPORT
This 45-year old male with no previous or family history of cancer came to us in April 2010, he presented with headache, vomiting and paresthesia of left half of the body, followed by left sided hemiparesis and seizure resulting in hospitalization.
CT scan of the brain showed a large high-density space-occupying mass in right frontal region with no evident meningeal attachment (fig. 1).
Figure 1.
CT-Scan (a, b) showing large increased attenuating regular space occupying mass lesion in right frontal region without meningeal involvement.
The patient underwent surgery with a partial resection of tumor was performed due to the presence of the tumor in the vicinity of internal capsule and basal ganglia. The symptoms improved and the patient was put on anticonvulsant therapy. Histology demonstrated a malignant tumor with pigmented cells and positive immunohistochemistry for S100, human melanoma black-45(HMB-45) suggestive of malignant melanoma (Fig. 2). Subsequently, the patient had a thorough examination in search of any cutaneous melanoma. Clinical, radiological and ophthalmologic examination did not reveal any primary site.
Figure 2.
Microphotograph of intraparenchymal tumor biopsy showing a) Sheets of anaplastic round tumor cells with focal pigment (H & E x 125 x digital magnification) b) Tumor showing large vesicular nuclei, prominent nucleoli and cytoplasmic melanin pigment (H & E x 525 x digital magnification) c) Positive immuno-expression of HMB 45 and d) S100 in tumor cells (DAB x 125 x digital magnification).
The patient then received radiotherapy with one anterior and one lateral wedge pair fields with unequal weighting. Patient received total dose of 56Gy in 28 fractions in 51/2 weeks. Post treatment patient did not have significant improvement in symptoms with radiological evidence of residual disease (Fig. 3). Patient was managed conservatively with steroids along with CCNU and interferon chemotherapy. The patient died due to diffuse intracranial dissemination in September 2010.
Figure 3.
CT-Scan (a, b) showing post-radiotherapy residual disease in right fronto-parietal region.
DISCUSSION
Primary intraparenchymal brain melanoma without leptomeningeal involvement may arise from the developmental neural crest cells in brain parenchyma and are associated with poor prognosis inspite of using all available treatment options [3, 4]. The diagnosis of primary brain melanoma is seldom made clinically or radiologically, it is usually confirmed by histopathology and immunohistochemistry including a combination of S100 (found in almost all melanocytes and few other neural crest tumors) and HMB 45 (specific for melanomas). Surgical resection with aggressive adjuvant treatment including post operative radiotherapy and chemotherapy forms the mainstay of the treatment which may alleviate the clinical symptoms, but without significant improvement in survival [1].
The mean survival of these patients is about 6-20 months depending on the adequate surgical resection of the lesion and histological subtype [1, 5, 6].
Our patient also underwent limited surgery and local radiotherapy, but had a poor treatment outcome.
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