Rheumatology: Current Research
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Baker’s Cyst with Purulent Intramuscular Cysts

Kenji Yamada^*, Ryo Hazue and Ryo Rokutanda ^*Correspondence: Kenji Yamada, Department of Rheumatology, Kameda Medical Center, Kamogawa, Chiba, Japan, Email:

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Case Description

An 85-year-old man with rheumatoid arthritis complained of gradual onset of increased pain in the left calf that began four weeks before the visit, with swelling appearing a week later. He denied having fever, chills, malaise, or joint pain. Medications for rheumatoid arthritis included prednisone (6 mg), iguratimod (25 mg), and filgotinib (100 mg). Physical examination revealed tenderness and swelling in the left calf, without redness or warmth. No muscle weakness, paresthesia or signs suggestive of arthritis were observed. Ultrasonography did not reveal deep vein thrombosis. An enhanced Computed Tomography (CT) of the legs revealed bilateral Baker’s cysts with multiple cysts in the left calf, one of which contained air as shown in Figures 1A-C. Purulent drainage fluid was collected during the Incision and Drainage (I and D) procedures as shown in Figure 1D. Antibiotics were administered after I and D. An enhanced CT performed 12 days after I and D showed a residual Baker's cyst and shrinking intramuscular cysts, with no connection between them as shown in Figure 1E. Despite the negative drainage fluid culture, antibiotics were administered for four weeks due to the purulent nature of the fluid and the presence of air on CT. His symptoms resolved with the treatment.

Figure 1: Enhanced Computed Tomography (CT) scans taken when the patient presented with symptoms revealed bilateral Baker's cysts, with multiple cysts in the medial head of the gastrocnemius muscle of the left calf, one containing air.

Note: (A) Coronal view of the bilateral lower limbs; (B) Sagittal view of the left lower limb; (C) 3D reconstructed image of the left lower limb; (D) Drainage fluid collected during an Incision and Drainage (I and D) procedure; (E) An enhanced CT taken 12 days after the Incision and Drainage (I and D) showed in left lower limb.

In this case, multiple cysts were most likely due to the dissection of a Baker's cyst into the medial head of the gastrocnemius muscle. Although rare, Baker’s cysts dissecting into muscles have been reported [1]. Additionally, an infected Baker’s cyst can be a rare cause of unilateral pain and swelling in the lower extremities [2]. However, there are no reports of dissected Baker’s cysts becoming infected. If these cysts were not infected, the Baker’s cysts might have ruptured into muscles, forming septa and becoming purulent. This is the first report of purulent intramuscular cysts complicated by a Baker’s cyst, highlighting a significant clinical finding.

Conflict of Interest

No disclosure.

References

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