Clinical Images: Joint pain with CHIK sign: a classic clinical diagnosis

The patient, a 38-year-old woman, presented with acute onset bilaterally symmetrical inflammatory polyarthritis of both large and small joints over a period of 20 days. She had no previous comorbidities. In addition, she had no history of antecedent events or substance abuse. Clinical examination revealed multiple tender joints with bilateral ankle tenosynovitis. Notably, she exhibited hyperpigmented, nonpruritic skin lesions over the tip of the nose with cutaneous thickening (A). Additional areas of hyperpigmentation were observed over the palms (B), knuckles, beneath the ear lobes, and on the pinnae. Further evaluation revealed high markers of inflammation (erythrocyte sedimentation rate 68 mm/1st hour, C-reactive protein 40 mg/L) with positive chikungunya serology (anti-chikungunya IgM). Her hormonal profile and autoimmune panel were normal. She was diagnosed with post chikungunya arthritis with classical CHIK sign (A and B). The patient was initiated on nonsteroidal anti-inflammatory drugs and low-dose glucocorticoids, leading to symptomatic improvement. Post chikungunya arthritis is a common clinical scenario in tropical countries. Nasal hyperpigmentation, initially thought to be a unique manifestation of chikungunya infection, has also been rarely observed in dengue.1 Increased intraepidermal melanin dispersion or retention triggered by virus is likely the cause of hyperpigmentation. A recent case series of six patients from India had described a phenotype named “COVID-19 nose” resembling “chik sign.”2 Although both viral diseases are associated with brownish black nasal hyperpigmentation with post-infective arthritis, there was a significant delay in the presentation in COVID-19 than chikungunya, which appears one to three weeks after fever defervescence. Disclosure form. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.