An Unusual Case of Psoriatic Arthritis With Secondary Lingual Lesions, Resembling Geographic Tongue.

Psoriatic arthritis (PsA) is a chronic inflammatory condition that impacts a significant proportion of individuals diagnosed with psoriasis. This report presents a rare case of a patient diagnosed with PsA who never had active psoriatic skin lesions but only a family history of psoriasis, with secondary lingual lesions, resembling geographic tongue (GT). A male patient, 24 years old, was referred with two painless erythematous areas resembling (without whitish borders, as in GT) rounded atrophic lesions on the dorsal surface of the tongue, resistant to any kind of antimicrobial/antifungal treatment for more than six months. The patient was diagnosed with PsA two years ago fulfilling the CASPAR (ClASsification for Psoriatic ARthritis) criteria. The patient never had active psoriatic skin lesions, but his father had psoriasis. The biopsy of lingual lesions showed moderate hyperkeratosis, spongiosis, and diffuse inflammatory infiltration of lymphocytes and neutrophils in the lamina propria as well as in the stratified squamous epithelium forming Munro's microabscesses at the superficial layers. The manifestation of the atypical psoriasiform, GT-like lingual lesions was considered as part of psoriasis manifestations and the patient was advised to follow regular checkups so that any major exacerbation of the systematic symptoms could be preemptively avoided. Not only GT but also atypical lingual GT-like reddish oral lesions may be considered as transient forms of psoriasis supporting an early diagnosis and monitoring of psoriasis/PsA.