A spiderweb clot in the CSF

Q: 42 years old male with no known previous history is brought to the ER with complaints of change in mental status, fever, and nuchal rigidity. CT scan of the head is unremarkable. The ER doc performed lumbar puncture and transferred the patient to ICU. You get a STAT call from the lab that a spiderweb clot formation is seen in the CSF sample. What does it mean?

Answer: 

A spiderweb clot in the collected CSF, also called cobweb,  is characteristic of cryptococcal and tuberculous meningitis. For reference see the picture shown below.

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References:

1. Staib F, Seibold M, Antweiler E, Zimmer C, Heitz J, Stoltenburg-Didinger G. Cerebrospinal fluid indices in cryptococcal and tuberculous meningitis: the spider web coagulum and its diagnostic significance. Mycoses. 1990 Jul-Aug;33(7-8):359-67. doi: 10.1111/myc.1990.33.7-8.359. Erratum in: Mycoses 1990 Nov-Dec;33(11-12):518. PMID: 2090936.

2. Daniel BD, Grace GA, Natrajan M. Tuberculous meningitis in children: Clinical management & outcome. Indian J Med Res. 2019 Aug;150(2):117-130. doi: 10.4103/ijmr.IJMR_786_17. PMID: 31670267; PMCID: PMC6829784.

3. Siroos B, Ahmadinejad Z, Tabaeizadeh M, Hedayat Yaghoobi M, Torabi A, Ghaffarpour M. Rare Association of Severe Cryptococcal and Tuberculosis in Central Nervous System in a case of Sarcoidosis. Med J Islam Repub Iran. 2014 Mar 11;28(1):22. PMID: 25250282; PMCID: PMC4154284.

4. Marx GE, Chan ED. Tuberculous meningitis: diagnosis and treatment overview. Tuberc Res Treat. 2011;2011:798764. doi: 10.1155/2011/798764. Epub 2011 Dec 21. PMID: 22567269; PMCID: PMC3335590.