Answer for BIR CoW 20 Oct 2024
Chronic Gout
Findings
Bony erosion involving head of proximal phalynx of great toe and head of 5th metatarsal of right foot with periarticular soft tissue swelling Bony erosion involving head of left 1st metatarsal with periarticular soft tissue swelling Osteopenic changes noted involving the bilateral tarsal bones Diffuse radioopacities noted involving the left fore foot IMPRESSION The above features are suggestive of chronic gout
Discussion
Gout is the most common cause of inflammatory arthritis in men and its prevalence is rapidly expanding in the general population. It is associated with an excess of uric acid in the body. This results in supersaturation of uric acid in body tissues and fluids resulting in urate deposition. The disease has four phases which includes asymptomatic hyperuricemia, acute, intercritical, and chronic gout. The diagnosis of gout is confirmed by the presence of intracellular MSU crystals in a joint aspirate. RADIOGRAPHIC FINDINGS : Erosions : Juxta-articular cortical irregularity and depression +/− overhanging edge +/− and sclerotic margins.Findings seen in at least two planes Erosions adjacent to tophus (causative agent) CT is most sensitive. Synovial proliferation : Synovial thickening +/− enhancement on post contrast images +/− increased vascularity on Doppler imaging. Tophus : Eccentric high-density soft tissue swelling from chronic granulomatous response to MSU crystals Can be intra- or extra-articular Characteristic US appearance: hypoechoic peripheral rim/halo and hyperechoic/heterogeneous center. Bone marrow edema : Uncommon/minimal, specifically centered around erosion If extensive, think of inflammatory arthritis or infection, whether associated with the underlying diagnosis or not Only MRI can demonstrate bone marrow edema Cartilage involvement : MSU crystals deposit on articular cartilage surface (anechoic curvilinear band paralleling the cortex) giving “double contour sign” Hydroxyapatite deposition is within cartilage substance US is most sensitive Joint effusion : Anechoic fluid in the joint recess/space not specific sign unless accompanied by small numerous hyperechoic foci +/− “snow storm appearance” Aspirate to confirm gout and exclude infection. Radiographic findings of gout occur late in the disease and underestimate the degree of involvement. Characteristic radiographic findings of gout include, first MTP involvement, juxta-articular erosions with sclerotic margins and overhanging edges, preservation of joint spaces and periarticular bone density until late in the disease process. Osteoclasts are activated at the bone tophus interface, whereas osteoblasts are inhibited resulting in marked localized bone loss . Gout deposits around joints can be juxta-articular, intra-articular, and subchondral and usually do not demonstrate symmetric joint involvement. The tophus, the hallmark of chronic gout, is a soft tissue nodule representing the body's granulomatous immune reaction to MSU crystals. Dense calcification in the tophus is a late finding and may be associated with disturbance in calcium metabolism. Erosions are often located next to a tophus.
REFERENCES
Richette P, Bardin T. Gout. The Lancet. 2010;375(9711):318–328. [PubMed] [Google Scholar] Imaging Appearances in Gout Arthritis. 2013; 2013: 673401.2013 Mar 25. doi: 10.1155/2013/673401 PMCID: PMC3621383 PMID: 23585966 Dähnert W. Radiology review manual. Lippincott Williams & Wilkins. (2007).
Findings
Bony erosion involving head of proximal phalynx of great toe and head of 5th metatarsal of right foot with periarticular soft tissue swelling Bony erosion involving head of left 1st metatarsal with periarticular soft tissue swelling Osteopenic changes noted involving the bilateral tarsal bones Diffuse radioopacities noted involving the left fore foot IMPRESSION The above features are suggestive of chronic gout
Discussion
Gout is the most common cause of inflammatory arthritis in men and its prevalence is rapidly expanding in the general population. It is associated with an excess of uric acid in the body. This results in supersaturation of uric acid in body tissues and fluids resulting in urate deposition. The disease has four phases which includes asymptomatic hyperuricemia, acute, intercritical, and chronic gout. The diagnosis of gout is confirmed by the presence of intracellular MSU crystals in a joint aspirate. RADIOGRAPHIC FINDINGS : Erosions : Juxta-articular cortical irregularity and depression +/− overhanging edge +/− and sclerotic margins.Findings seen in at least two planes Erosions adjacent to tophus (causative agent) CT is most sensitive. Synovial proliferation : Synovial thickening +/− enhancement on post contrast images +/− increased vascularity on Doppler imaging. Tophus : Eccentric high-density soft tissue swelling from chronic granulomatous response to MSU crystals Can be intra- or extra-articular Characteristic US appearance: hypoechoic peripheral rim/halo and hyperechoic/heterogeneous center. Bone marrow edema : Uncommon/minimal, specifically centered around erosion If extensive, think of inflammatory arthritis or infection, whether associated with the underlying diagnosis or not Only MRI can demonstrate bone marrow edema Cartilage involvement : MSU crystals deposit on articular cartilage surface (anechoic curvilinear band paralleling the cortex) giving “double contour sign” Hydroxyapatite deposition is within cartilage substance US is most sensitive Joint effusion : Anechoic fluid in the joint recess/space not specific sign unless accompanied by small numerous hyperechoic foci +/− “snow storm appearance” Aspirate to confirm gout and exclude infection. Radiographic findings of gout occur late in the disease and underestimate the degree of involvement. Characteristic radiographic findings of gout include, first MTP involvement, juxta-articular erosions with sclerotic margins and overhanging edges, preservation of joint spaces and periarticular bone density until late in the disease process. Osteoclasts are activated at the bone tophus interface, whereas osteoblasts are inhibited resulting in marked localized bone loss . Gout deposits around joints can be juxta-articular, intra-articular, and subchondral and usually do not demonstrate symmetric joint involvement. The tophus, the hallmark of chronic gout, is a soft tissue nodule representing the body's granulomatous immune reaction to MSU crystals. Dense calcification in the tophus is a late finding and may be associated with disturbance in calcium metabolism. Erosions are often located next to a tophus.
REFERENCES
Richette P, Bardin T. Gout. The Lancet. 2010;375(9711):318–328. [PubMed] [Google Scholar] Imaging Appearances in Gout Arthritis. 2013; 2013: 673401.2013 Mar 25. doi: 10.1155/2013/673401 PMCID: PMC3621383 PMID: 23585966 Dähnert W. Radiology review manual. Lippincott Williams & Wilkins. (2007).
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!