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Neuroradiology Case of the Week

Case 73

Ravinder Sidhu MD, Ramon deGuzman MD, Sven Ekholm MD, PhD
and P-L Westesson MD, PhD, DDS

Clinical Presentation: A 53-year-old female, with a past history of breast cancer, presented with right upper and left extremity weakness.

Radiological Findings:  Non-contrast enhanced head CT showed two hypodense lesions with ill-defined margins seen in the left frontal and temporal lobes. The rest of the brain parenchyma appeared normal (Fig. 1A). Contrast enhanced CT showed thin, irregular subdural enhancement along the left frontotemporal convexity. Brain parenchyma did not reveal any additional findings (Fig. 1B). Bony window revealed diffuse, multiple, mottled lytic areas in the clivus and skull base suggestive of metastatic deposits (Fig. 1C). T2-weighted MR images showed increased signal areas in the left frontal and temporal region suggestive of vasogenic edema (Fig. 2A). Post-contrast MR showed thickened and nodular subdural enhancement along the left frontal and temporal regions indicating metastatic leptomeningeal enhancement (Fig. 2B). Axial FLAIR image showed hyperintense left frontal lesion along with effacement of adjoining sulci (Fig. 3).

Diagnosis: Leptomeningeal carcinomatosis

Discussion:  Leptomeningeal carcinomatosis occurs in approximately 5% of patients with cancer. The most common cancers to involve the leptomeningeal carcinomatosis are breast cancer, lung cancer, and melanomas. About 2 to 5% of patients with breast cancer will develop leptomeningeal carcinomatosis, usually late in the course of disease. Leptomeningeal cancer can invade the brain and spinal parenchyma, nerve roots, and vessels that supply the central nervous system. This can result in focal signs and symptoms such as seizures, stroke-like syndromes, and isolated neurological deficits [1].
    A positive CSF cytology may be seen in 50% of patients on initial lumbar puncture and in 85% of patients who undergo three high volume lumbar punctures [2].
    Radiologically, non-contrast enhanced CT usually does not show any abnormality. Contrast enhanced CT may show meningeal enhancement. However, contrast enhanced MR is more sensitive than contrast enhanced CT, especially when most of the meningeal enhancement lies against the skull vault. Normal meningeal enhancement is visualized as a thin, markedly discontinuous rim covering the surface of the brain. The enhancement is primarily seen in the dura and venous structures [3].
    Meningeal enhancement can be seen due to any cause that causes meningeal irritation such as meningitis (tubercular/fungal), transient post-operated meningeal enhancement, subdural hematoma, and carcinomatosis. In inflammatory meningitis, most often enhancement is visualized along the vasculature, in the sulci, or in the basal cisterns. Transient enhancement in post-operated state is due to blood in subarachnoid space [4]. In leptomeningeal carcinomatosis, enhancement depends upon the mode of spread of tumor cells. It is usually seen as diffuse, nodular, and sheet like enhancement.

References:

1. Grossman SA, Krabak MJ. Leptomeningeal carcinomatosis. Cancer Treat Rev. 1999; 25:103-119.
2. Theodore WH, Gendelman S. Meningeal carcinomatosis. Arch Neurol. 1981; 38:696-699.
3. Chamberlain MC, Sandy AD, Press GA. Leptomeningeal metastasis: a comparison of gadolinium-enhanced MR and contrast-enhanced CT of the brain. Neurology 1990; 40:435-438.
4. Sze G, Soletsky S, Bronen R, Krol G. MR imaging of the cranial meninges with emphasis on contrast enhancement and meningeal carcinomatosis. AJR Am J Roentgenol 1989; 153: 1039-1049.