BACKGROUND: Calcinosis cutis, a disease characterized by the presence of calcium deposits in the skin, is classified into four types according to etiology: dystrophic, metastatic, iatrogenic and idiopathic. The dystrophic form is the most common while the idiopathic one is the rarest, but specific incidence and frequency data are not available in scientific literature. OBJECTIVE: Calcinosis cutis circumscripta is a very rare form of idiopathic calcinosis cutis arising in the second half of life. It typically involves the extremities and is associated with prior trauma and scleroderma. We dealt with a very rare form of calcinosis cutis circumscripta in a healthy patient, for whom surgical excision revealed to be an effective and successful treatment. METHODS AND MATERIALS: We present the case of a 46-year-old woman affected by idiopathic circumscripta calcinosis cutis of the left knee, successfully treated by surgical removal. DISCUSSION: Medical and surgical treatment are options to cure calcinosis cutis. Medical therapy is not very effective. Surgical excision has shown to be beneficial, as it can provide a symptomatic relief. However, since calcinosis cutis limits are not always well defined a recurrence of the lesions may occur.