A case of lupus carcinoma in a patient with lupus tuberculosis is presented. Skin manifestations of tuberculosis, symptoms of «apple jelly» and Pospelov signs are described, and laboratory and instrumental tests are presented. The patient has clinical, dermatoscopic, and ultrasonographic signs of lupus carcinoma (infiltrating basal cell carcinoma of the skin) confirmed by cytological and pathological examination. Lupus-carcinoma is a rare and severe complication of chronic dermatoses with abnormal regeneration, particularly lupus tuberculous and erythematosus. Lupus-carcinoma occurs mainly in patients with lupus tuberculosis (0.5–4% of cases); the interval between the disease onset and verification of skin cancer can vary from 10 to 40 years or more. Risk factors for malignancy include a prolonged course of the underlying disease, mechanical and burn injury, occupational hazards, exposure to ionizing, ultraviolet or X-ray radiation, concomitant chronic inflammatory conditions, abnormal skin pigmentation, prolonged immunosuppression, age older than 40 years, male gender, types I and II of skin photosensitivity, personal and family oncological history. The clinical presentation of lupus carcinoma includes a predominantly solitary deep ulcer-infiltrating skin defect or ulcer-exophytic mass localized in lupus tuberculous or erythematosus lesions. Important clinical features of lupus carcinoma are the irregular shape and cartilaginous density of the mass, the absence of a skin pattern on the surface of the element, the presence of infiltrated, undermined, and roll-shaped edges with multiple telangiectasias, glomerated with adjacent tissues, increased bleeding tendency and soreness on palpation. The diagnosis of lupus carcinoma is verified by pathological examination of the biopsy specimen with histological signs of invasive squamous cell or infiltrating basal cell skin cancer.