Perforating granuloma annulare mimicking papulonecrotic tuberculid
A 19-year-old female patient was referred to the dermatologist because of lesions on the\nhands, elbows and knees of three-year duration. On examination, the patient presented\nerythematous papules, with a crusted umbilicated center, localized on the extensor\nsurfaces of the limbs and dorsal aspect of the hands. She also had some pustules on the\npalmar surface of the fingers ( and ).\nAs comorbidity, she has had a diagnosis of systemic lupus erythematous ten years\npreviously, conforming to the following criteria: discoid and malar rash,\nphotosensitivity, coarse speckled nuclear antinuclear antibody and thrombocytopenia. She\nhad previously been treated with oral corticosteroids, cyclosporine and\nmethylprednisolone pulse therapy. Over the last six years, the disease was controlled\nand maintenance therapy was being performed with hydroxychloroquine.\nSimultaneously to the skin changes, the patient had developed cervical adenomegaly,\noriginating a 5centimeters diameter conglomerate. Fine-needle aspiration diagnosed a\nchronic granulomatous lymphadenitis with caseous necrosis. Ziehl-Neelsen stain and\nculture of mycobacteria resulted both negative in the aspirate. The patient showed a\nstrong reaction to tuberculin (28mm), leading to the formation of bullae, necrosis and a\nresidual atrophic scar ().\nThe initial diagnostic hypothesis was papulonecrotic tuberculid secondary to lymph node\ntuberculosis.\nThe patient was referred to the infectology clinic and was started on antituberculous\npolychemotherapy standardized in Brazil, consisting of rifampicin, isoniazid,\npyrazinamide and ethambutol.\nHistopathology of the skin revealed a palisading granuloma in communication with the\nepidermal surface and constituting an area of perforation. The granuloma was surrounded\nby a peripheral infiltrate of histiocytes and lymphocytes and had a central area of\nmucinous degeneration of collagen. The absence of necrosis and vascular involvement and\nthe typical histological findings of perforating granuloma annulare undermined the\ninitial clinical hypothesis that this was papulonecrotic tuberculid (-).\nPCR-based detection of Mycobacterium tuberculosis resulted negative in\na sample of a palmar pustule.\nIn the first weeks of antituberculous therapy, new papules or pustules stopped\nappearing. After six months, complete regression of the adenomegaly and cutaneous\nlesions was observed, including the palmar pustules.\nThroughout the evolution of the disease and its treatment the patient showed no signs of\nlupus activity and remained on maintenance therapy with anti-malarial.