A case of intracranial molluscum contagiosum virus infection diagnosed by metagenomic sequencing of cerebrospinal fluid.

Molluscum contagiosum is a common, self-limiting infectious disease of the skin caused by molluscum contagiosum virus (MCV). The disease primarily affects children, sexually active adults, and immunocompromised individuals. Transmission of the virus occurs by direct skin contact. Therefore, the virus is usually detected in the skin and genitals of patients. However, the diagnosis of intracranial infection by the virus is difficult if the skin/mucosa lessons are atypical or absent, and the presence of the virus in the cerebrospinal fluid has not been reported. We report a very rare case of intracranial infection by molluscum contagiosum virus. A 25-year-old girl was admitted to our hospital due to severe headache but no fever or other symptoms. Upon examination, some small flesh-colored flattened papules on both arms were noticed. Blood tests showed slightly reduced levels of CD3 and CD4 T lymphocytes. Three-dimensional time-of-flight magnetic resonance angiography (3D-TOF-MRA) and head magnetic resonance (MR) were both normal. Lumbar puncture was performed, and metagenomic sequencing was applied to the spinal fluid. The unique sequences of the molluscum contagiosum virus were identified in the fluid. The patient was then diagnosed with intracranial molluscum contagiosum virus infection. No special treatment was given. The headache gradually disappeared, and the patient was discharged. During our quarterly follow-up, the girl appeared normal, and her skin lesions disappeared. However, her CD3 and CD4 T lymphocyte counts were still slightly lower than the normal level. Our case shows that the application of metagenomic sequencing to cerebrospinal fluid is a sensitive and powerful means to detect pathogens causing intracranial infection. Keywords: Molluscum contagiosum; intracranial infection; metagenomics sequencing.