Cerebrospinal fluid immunocytochemical analysis and neuroimaging in the diagnosis of primary leptomeningeal melanoma

Abstract

A 20-year-old man presented with slowly progressing symptoms indicative of increased intracranial pressure. Two weeks later he underwent surgery for placement of a ventriculoperitoneal shunt. Cytological examination of the patient's cerebrospinal fluid (CSF) revealed atypical cells that contained no detectable melanin deposits, but proved to be immunocytochemically positive for monoclonal antibodies to melanocytic cells (HMB-45) and S-100 protein. Dermatological and ophthalmological examinations failed to demonstrate any abnormalities. On the basis of these findings, a diagnosis of primary leptomeningeal melanoma was made. Gadolinium-enhanced magnetic resonance (MR) images of the brain and spinal regions obtained 2 months after admission demonstrated typical widespread leptomeningeal enhancement. Results of technetium-99m-hexakis (2-methoxyisobutyl isonitrile) single-photon emission computerized tomography (99mTc-MIBI SPECT) scanning revealed intense uptake of the isotope in the leptomeningeal regions and some cisterns. The patient's condition progressively worsened and he died 5 months after admission. The diagnosis was confirmed at autopsy. Immunocytochemical analysis of CSF performed using HMB-45 and S-100 protein antibodies is important for the diagnosis of leptomeningeal melanoma because of the test's simplicity, high specificity, and sensitivity. Gadolinium-enhanced MR imaging is used to demonstrate the extent of the leptomeningeal melanoma. An additional and supplemental neuroimaging modality, 99mTc-MIBI SPECT scanning has good potential for the detection and diagnosis of leptomeningeal melanoma.

Ascending paralysis from malignant leptomeningeal melanomatosis

“…Only one report of tetraparesis has been described previously; in that case, paralysis occurred late in the patient's 1 year course. In the present case, ascending paralysis occurred rapidly in the 5 week course 3. In case reports, two of the longer surviving patients were treated with radiation or intrathecal interleukin 2 4 5.…”

“…Surgical biopsy or the presence of melanin containing cells in CSF, provided they are present at detectable levels, is often the only means of diagnosis. Melanoma cells have also been identified using Fontana–Masson or dopa reactions, as well as with direct visualisation using electron microscopy 2 3…”

A case of intracranial hypotension complicated with hydrocephalus

“…The pathogenic mechanism of extradural enhancement may be attributable to the vascular dilatation of dural arteries and medullary and cortical veins to compensate for reduced CSF volume and a greater volume of gadolinium remaining in the dilated extradural microvasculature and diffusing into the extradural interstitial fluid (7,20). Non-hypotensive pachymeningeal enhancement may result from various dural tissue responses to infection, immunological mechanisms, systemic or regional granulomatosis, cancer metastasis, various connective tissue diseases, or other unknown causes (3,12,14,17,32). That is why the biochemical and microbiological examinations of CSF and the histopathological evaluation of dura and arachnoid mater were needed to assure the diagnosis of ICH.…”

Primary Pineal Malignant Melanoma

“…Atypical cells found in the CSF bore pleomorphic nuclei with strongly eosinophilic cytoplasm typical of malignant melanoma. Immunostaining with HMB45 and melan-A were confirmatory for the diagnosis of melanoma, and such stains may be useful in establishing a cytopathologic diagnosis in the case of amelanotic cancers or early cancers that seed only a few atypical cells into the CSF [23,24,25]. …”