Correct answer to Q1 is:  No signs of synovitis in the joints

Discussion

No increased synovial thickness, joint effusion or power Doppler signals were detected, which ruled out rheumatoid arthritis. Subcutaneous thickening was predominant, and the patient was not aware of any recent trauma or injury. The image findings, in addition to the clinic of worsening during winter days and the physical exam showing multiple erythrocyanotic lesions on the fingers, lead to a suspicion of erythema pernio.

Image 2: A and B. Proximal interphalangeal joint of the second and fifth right digits. Both with focal tickening of the subcutaneous tissue (white arrow). Absence of vascularization on power Doppler. No synovial thickening in the joints of the right hand.

Image 3: A and B. Left hand proximal interphalangeal joint. Focal tickening of the subcutaneous tissue (arrow). Absence of vascularization on power Doppler. No synovial thickening.

Correct answer to Q2 is: Considering the involvement of deeper structures as synovitis and cortical erosion, rheumatoid arthritis must be the diagnosis.

Additional discussion

Erythema pernio, also known as chilblains, is a rare inflammatory skin condition characterized by painful, red or purple lesions on the extremities, typically in response to exposure to cold conditions. It primarily affects the fingers and toes. In contrast to conditions like rheumatoid arthritis, which affects joints and soft tissues, erythema pernio is essentially a skin-related disease.

In the context of erythema pernio, the use of ultrasound is not a standard diagnostic approach. However, in this case it was essential to exclude the involvment of deeper structures like joints and tendons rather than the superficial layers of the skin.

The pathophysiology is unknown, but it is associated with vasospasm, particularly when the patient is exposed to cold, damp conditions for a prolonged period. A comprehensive history and physical examination is essential for the assessment and diagnosis of pernio. Inquiries about the timing of the appearance of the lesions, recent cold exposures, and symptom improvement upon removing cold exposure are instrumental in narrowing down the potential causes to pernio or other vasospastic diseases. Skin biopsies shows nonspecific findings and are not helpful for the diagnosis.

The disease is largely considered idiopathic, although there are instances of secondary pernio. One notable form of secondary pernio is linked to systemic lupus erythematosus, leading to the development of chilblain lupus erythematosus, and also Raynaud phenomenon, acrocyanosis, cryoglobulinemia and cold panniculitis should be considered.

Conclusion

Dermatological conditions can often be diagnosed by clinical history and physical exam, however the use of ultrasound as an auxiliary tool is growing. In the context of our case with a suspicion of erythema pernio, ultrasound was essential to rule out involvement of the deeper structures, as the condition primarily involves the superficial layers of the skin. This is particularly important when trying to differentiate erythema pernio from conditions like rheumatoid arthritis, which affect these deeper structures.

Conflicts of Interest:

The author declares no conflict of interest.

References

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