Primary Diffuse Leptomeningeal Melanomatosis Initially Misdiagnosed as Type III Sturge-Weber Syndrome: A Case Report and Systematic Review of the Literature.

OBJECTIVE

The aim of this study was to report a rare case of primary diffuse leptomeningeal melanomatosis (PDLMM) initially misdiagnosed as type III Sturge‒Weber syndrome (SWS) and to review the literature on PDLMM to summarize its clinical features. Moreover, we aimed to explore the underlying reasons for the initial misdiagnosis.

METHODS

We reported the diagnosis and treatment of a rare case of PDLMM misdiagnosed as type III SWS. Then, we performed a systematic review of the literature to analyze the clinical features of these diseases.

RESULTS

An 8-year-old boy presented with stroke-like syndrome. Brain magnetic resonance imaging revealed diffuse cortical surface and subcortical lesions that were hyperintense on T1-weighted images and hypointense on T2-weighted images. The third cytology of the cerebrospinal fluid revealed characteristic melanoma cells. The diagnosis was confirmed by meningeal biopsy. Together with the 21 previously reported cases, we found that age was not related to any clinical features except for cognitive impairment. Additionally, compared to the 2 patients who were initially misdiagnosed with type III SWS, the other 20 patients detected higher cerebrospinal fluid protein concentrations. The median overall survival of patients with PDLMM was 5 months from diagnosis.

CONCLUSIONS

A definite diagnosis of PDLMM requires a combination of clinical features and clinical physicians with sufficient experience. The signal changes of cortical and subcortical lesions on magnetic resonance imaging are key to making early decisions regarding whether to perform a biopsy. Illustrating the similarities and differences between PDLMM and SWS can avoid misdiagnosis.