Case of keratosis lichenoides chronica with atypical sarcoidal granulomatous inflammation

ABSTRACT Keratosis lichenoides chronica (KLC) is a rare chronic disease characterized by violaceous, papular and nodular lesions typically arranged in a linear and reticulate pattern. The etiology of KLC is unknown, but it may be associated with internal diseases such as hypothyroidism, glomerulonephritis and lymphoproliferative disorders. Herein, we describe the case of 44‐year‐old male patient with characteristic lesions of KLC on the trunk and extremities, present for 12 years. The clinical diagnosis was proven by histopathological examination on several occasions. In the years following the diagnosis of KLC, he developed bilateral hilar and multiple mediastinal, cervical and inguinal lymphadenopathies and hepatosplenomegaly. In 2000, diffuse interstitial and then reticulonodular pulmonary infiltrates associated with fever, weight loss, malaise and subcutaneous nodules developed. Biopsies taken from peripheral and mediastinal lymph nodes, pulmonary parenchyma, pleural tissue, bone marrow and skin showed non‐necrotizing granulomas, indicating a sarcoidal granulomatous reaction. Characteristic histopathological findings and the absence of atypical cells, clonality and a high proliferative index excluded lymphomas. Furthermore, detailed tests showed no evidence of an infectious granulomatous disease. As far as we know, this is the first reported case of KLC associated with a sarcoidal granulomatous reaction.