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October 22, 2021

Pontine Lesion

Pontine Lesion, large cystic lesion filled with grumous material within the right basis pontis

Pontine Lesion, metastatic squamous cell carcinoma Pontine Lesion, metastatic squamous cell carcinoma


This middle-aged patient presented with left-sided upper and lower extremity weakness. MRI demonstrated a 2.5 cm cystic ring-enhancing lesion in the pons. The patient’s condition deteriorated and they expired.  An autopsy was performed.


Which of the following would best complete the following sentence based on the gross (Figure #1) and microscopic (Figures #2 and #3 ) findings? 

The patient has a history of ______.

A. Bacterial sepsis

B. Large hilar lung mass

C. Multiple sclerosis

D. Eating raw pork


Answer: Large hilar lung mass

Figure #1 shows large cystic lesion filled with grumous material within the right basis pontis (pons). The location of this pontine lesion would account for the patient’s left-sided weakness. The two most common differential diagnoses based on the gross appearance alone are bacterial abscess and metastasis. Figures #2 and #3 show morphologic features of metastatic squamous cell carcinoma.  This patient had a long and significant history of cigarette smoking. Brain metastases may mimic bacterial abscess on neuroimaging studies and gross examination.

Racemose neurocysticercosis may form large cystic structures, but these typically are thin-walled fluid-filled cysts with a smooth inner surface. The demyelinating lesions of multiple sclerosis may show incomplete ring enhancement that is often incomplete (“open ring sign”) on MRI. It is not typical for the lesions of multiple sclerosis to undergo necrosis (however read about Schilder’s disease). Neither of these entities would contain neoplastic squamous cells.  



Yang SY, Lines WW, Vásquez CM, For The Cysticercosis Working Group In Perú. Racemose Neurocysticercosis. Am J Trop Med Hyg. 2020 Apr;102(4):703-704. doi: 10.4269/ajtmh.19-0868. PMID: 32242515; PMCID: PMC7124892.

Masdeu JC, Moreira J, Trasi S, Visintainer P, Cavaliere R, Grundman M. The open ring. A new imaging sign in demyelinating disease. J Neuroimaging. 1996 Apr;6(2):104-7. doi: 10.1111/jon199662104. PMID: 8634482.

Jarius S, Haas J, Paul F, Wildemann B. Myelinoclastic diffuse sclerosis (Schilder’s disease) is immunologically distinct from multiple sclerosis: results from retrospective analysis of 92 lumbar punctures. J Neuroinflammation. 2019 Feb 28;16(1):51. doi: 10.1186/s12974-019-1425-4. PMID: 30819213; PMCID: PMC6396538.