Leptomeningeal metastases from a primary central nervous system melanoma: a case report and literature review

Abstract

Primary central nervous system (CNS) melanoma is a type of rare and aggressive tumor that can easily spread to the leptomeninges, and in fact, leptomeningeal metastasis is one of the most serious complications in patients with this carcinoma. Prognosis is extremely poor if a CNS melanoma has metastasized, and there are no effective treatments. Here, we present a case of a 37-year-old woman who presented with horizontal diplopia and progressive headache. Magnetic resonance imaging findings were consistent with the diagnosis of melanoma. The results of cytological examination of cerebrospinal fluid (CSF) showed malignant cells characteristic of melanoma. No extracranial lesions were observed. All of the available evidence confirmed a diagnosis of leptomeningeal metastases from a primary CNS melanoma. The patient received aggressive treatment, which consisted of concurrent radiotherapy and weekly intra-CSF methotrexate (MTX) followed by adjuvant monthly intra-CSF MTX. Her survival time was 13 months after diagnosis. This case report suggests that the modality of concurrent radiotherapy and weekly intra-CSF MTX followed by adjuvant monthly intra-CSF MTX may be used as the mainstay of treatment for such patients.

Figure 1

Imaging findings for brain. (A) Computed tomography image showing an isodense or slightly hyperdense lesion in the left temporal lobe (CT value: 45 to 61). Magnetic resonance image showing a 6-mm abnormal signal in the left temporal lobe, which was hyperintense on T1-weighted images (B), hypointense on T2-weighted images (C), slightly hyperintense on fluid-attenuated inversion recovery images (D), and mild enhancement with gadolinium contrast (E). Punctate and linear enhancement in the sulci and gyri of the cerebellum can be observed (F).

Figure 2

Malignant melanoma cells in the cerebral spinal fluid. (A, B) Round or oval tumor cells with different sizes were scattered, and presented as pseudopodia-like protrusions on cell membranes, with basophilic characteristics. Cells had round nuclei, large and distinct nucleoli, coarse and unevenly distributed chromatin, and particles in the nucleus or cytoplasm. (Liquid-based cytology, Papanicolaou staining, ×400).