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Cerebrospinal fluid cytology in a case of primary diffuse leptomeningeal and pineal melanocytic lesion, with histological confirmation.

Sir, Primary central nervous system (CNS) melanocytic neoplasms are lesions that arise from the leptomeningeal melanocytes of the cranial and spinal compartments, occurring both as discrete masses and diffuse proliferations. Even the intraventricular and pineal region lesions are leptomeningeal in origin. In their circumscribed form, they may occur as melanocytoma, with an annual incidence of approximately 1 per 10 million population, and the malignant counterpart melanoma, with an annual incidence of 0.005 cases per 10 000 population. The diffuse proliferations, namely melanocytosis and the malignant counterpart melanomatosis, generally occurring before the age of 2 years in the setting of dermatological syndromes such as neurocutaneous melanosis, are even rarer, with no population-based incidence available. Radiological studies are of limited value in the pre-operative diagnosis of these lesions and in differentiating them from other pigmented tumours of the leptomeninges. We describe the cytological findings of a primary diffuse leptomeningeal and pineal melanocytic neoplasm, with subsequent histological confirmation, in a 75-year-old woman, whose symptoms and clinical signs lasted several years and increased rapidly and fatally in 6 months. The patient was referred to us for sudden worsening of headache, dizziness, tremors of both upper extremities and altered personality over the previous 20 days. Dating back to 1998, she had been suffering from headache, mental deterioration, hearing loss and fall of visus, although not compromising her self-sufficiency. She had repeated computed tomography (CT) and magnetic resonance imaging (MRI) scans, which had shown progressive ischaemic changes with mild ventricular dilatation and bi-hemispherical multifocal ‘calcified’ T1-hyperintense and T2-hypointense non-enhancing micronodules in the leptomeninges and in the pineal region. All were a few millimeters in maximum dimension, fairly demarcated with no mass effect, and stable over time. The clinical and neuroradiological presumptive diagnosis had been of age-related changes overlapping the sequelae of an infective process, possibly parasitic (cysticercosis) (Fig. 1). In May 2006, on admission, neurological work-up confirmed symptoms of raised intracranial pressure. CT and MRI scans confirmed the nodularities located in the supraand infratentorial subarachnoidal and periventricular spaces, namely frontal bilateral and right temporo-polar regions, and cerebellar vermis. The pineal mass, protruding into the III ventricle, was still non-enhancing but had increased in size up to 15.45 mm in maximum dimension. For the treatment of hydrocephalus, an endoscopic third ventriculostomy was performed. Cerebrospinal fluid (CSF) was collected both for cytopathology and microbiological analysis. A pineal biopsy was performed. The CSF specimen appeared pink-red. It was processed in a routine fashion and stained with haematoxylin and