Sarcoidosis induced by anti-PD1 or anti-PDL1 agents such as atezolizumab has recently been reported. It has been suggested that the predilection of sarcoidosis to affect scars is due to the presence of antigens or foreign bodies that can serve as a stimulus for granuloma formation. However, to the best of our knowledge, sarcoidosis-specific skin lesions have not to date been reported involving xanthelasma. We report a patient who developed specific lesions of sarcoidosis infiltrating some xanthelasmata 6 months after starting treatment with atezolizumab. A 69-year-old woman was referred to the dermatology department for infiltration of xanthelasmata. The patient was being treated with atezolizumab for metastatic uterine carcinosarcoma. Cutaneous biopsy from an infiltrated xanthelasma and from still yellow, no infiltrated xanthelasma showed differing proportions of foamy histiocytes and sarcoid granulomas. On physical examination, erythemato-marronaceous papules clustered on both knees, and not previously detected by the patient, were observed. The biopsy showed sarcoid dermal granulomas with foreign bodies. A chest computerized tomography scan was consistent with intrathoracic involvement of sarcoidosis. Endobronchial ultrasound-guided transbronchial needle aspiration of a mediastinal lymphadenopathy showed epithelioid cell granulomas. Histopathologically, the foamy histiocytes of xanthelasma seem to be replaced by or evolve to epithelioid cells to form sarcoid granulomas. The possible pathogenic mechanism is discussed. Dermatologists and dermatopathologists should bear in mind that sarcoidosis can present as infiltration of pre-existing xanthelasmata.
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