Answer for BIR CoW 21 May 2023
MYCETOMA -KNEE
Findings
Multiple T1 hypointense/T2 heterointense soft tissue lesion noted involving deep infrapatellar region and medial recess of right knee joint with multiple clustered discrete T2 hyperintense areas with intervening hypointense septations and adjacent synovial thickening eroding into the anteromedial aspect of tibia It also involves subcutaneous plane with multiple discharging sinuses in intermuscular plane and extends to involve knee joint cavity The soft tissue lesion also noted involving the patellar tendon and tibial tuberosity with surrounding bone marrow perilesional STIR hyperintensity noted in metaphysis of tibia Fluid noted in knee joint cavity and suprapatellar fossa IMPRESSION Suggestive of mycetoma of knee joint with osteomyelitis of proximal tibia
Discussion
Mycetoma is a debilitating chronic granulomatous infection by true fungi (eumycetoma) or by bacteria of the order Actinomycetales (actinomycetoma). It affects the subcutaneous tissues and may extend to involve deeper structures The infection painlessly burrows deeply until it reaches the bone. If untreated, it can lead to significant destruction and deformity. Biopsy or microbiological culture can provide the diagnosis, but this may not always be possible. Mycetoma is characterized by the formation of aggregates of the organism, known as ¨grains¨, which are found within abscesses surrounded by abundant granulation tissue. Ultrasound showed distinct hyperechoic foci within a hypoechoic mass This could account for the appearance we observed on MRI of conglomerates of small (2-5 mm) round hyperintense lesions, representing the granulation tissue, surrounded by low-signal-intensity rim, representing intervening fibrous septa. The central low-signal-intensity dot is the result of susceptibility effect caused by the presence of fungal grains. This is a unique appearance, that appears to be highly suggestive of mycetoma and it is called dot-in-circle
DIFFERENTIAL DIAGNOSIS
Neoplasm of soft tissue
Tuberculous infection
REFERENCES
[1] Chhem RK, Wang S, Jaovisidha S, Smit P, Friedman L, Bureau NJ, Cardinal E. (2001) Imaging of fungal, viral, and parasitic musculoskeletal and spinal diseases. Radiol Clin North Am Mar; 39(2):357-78 (PMID: 11316364)
[2] Ispoglou SS, Zormpala A, Zormpala A, Sipsas NV (2003) Madura foot due to Actinomadura madurae: imaging appearance. Journal Clin Imaging 27 (233-235) (PMID: 12823917)
[3] Sarris I, Berendt AR, Athanasous N, Ostlere SJ, OSIRIS collaborative group. (2003) MRI of mycetoma of the foot: two cases demonstrating the dot-in-circle sign. Skeletal Radiol Mar, 32(3):179-83. Epub 2003 Jan28. (PMID: 12605286)
Findings
Multiple T1 hypointense/T2 heterointense soft tissue lesion noted involving deep infrapatellar region and medial recess of right knee joint with multiple clustered discrete T2 hyperintense areas with intervening hypointense septations and adjacent synovial thickening eroding into the anteromedial aspect of tibia It also involves subcutaneous plane with multiple discharging sinuses in intermuscular plane and extends to involve knee joint cavity The soft tissue lesion also noted involving the patellar tendon and tibial tuberosity with surrounding bone marrow perilesional STIR hyperintensity noted in metaphysis of tibia Fluid noted in knee joint cavity and suprapatellar fossa IMPRESSION Suggestive of mycetoma of knee joint with osteomyelitis of proximal tibia
Discussion
Mycetoma is a debilitating chronic granulomatous infection by true fungi (eumycetoma) or by bacteria of the order Actinomycetales (actinomycetoma). It affects the subcutaneous tissues and may extend to involve deeper structures The infection painlessly burrows deeply until it reaches the bone. If untreated, it can lead to significant destruction and deformity. Biopsy or microbiological culture can provide the diagnosis, but this may not always be possible. Mycetoma is characterized by the formation of aggregates of the organism, known as ¨grains¨, which are found within abscesses surrounded by abundant granulation tissue. Ultrasound showed distinct hyperechoic foci within a hypoechoic mass This could account for the appearance we observed on MRI of conglomerates of small (2-5 mm) round hyperintense lesions, representing the granulation tissue, surrounded by low-signal-intensity rim, representing intervening fibrous septa. The central low-signal-intensity dot is the result of susceptibility effect caused by the presence of fungal grains. This is a unique appearance, that appears to be highly suggestive of mycetoma and it is called dot-in-circle
DIFFERENTIAL DIAGNOSIS
Neoplasm of soft tissue
Tuberculous infection
REFERENCES
[1] Chhem RK, Wang S, Jaovisidha S, Smit P, Friedman L, Bureau NJ, Cardinal E. (2001) Imaging of fungal, viral, and parasitic musculoskeletal and spinal diseases. Radiol Clin North Am Mar; 39(2):357-78 (PMID: 11316364)
[2] Ispoglou SS, Zormpala A, Zormpala A, Sipsas NV (2003) Madura foot due to Actinomadura madurae: imaging appearance. Journal Clin Imaging 27 (233-235) (PMID: 12823917)
[3] Sarris I, Berendt AR, Athanasous N, Ostlere SJ, OSIRIS collaborative group. (2003) MRI of mycetoma of the foot: two cases demonstrating the dot-in-circle sign. Skeletal Radiol Mar, 32(3):179-83. Epub 2003 Jan28. (PMID: 12605286)
Note:
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!
We do not discourage differential diagnosis. But all the differentials must satisfy the findings noted in the case.
If you feel you have answered rightly but cannot find your name in the above list, please call 09551942599.
Did you Know?
The order in which the names appear in this winner's list is based on the time of submission. The first person to send the correct answer gets his/her name on top of the list!