A 19-year-old female patient received risperidone 3 mg twice daily for schizophrenia. She did not have nipple discharge before taking the drug. After taking the drug, nipple discharge occurred intermittently. One year later, a mass with pain in the right breast was found, which could not be alleviated after treatments with Rupi Sanjie capsules (乳癖散结胶囊), cefdinir, ibuprofen, rifampicin, and isoniazid and continued to increase, accompanied by bilateral knee pain, nodular erythema and tenderness of lower limbs. Laboratory tests showed white blood cell count 18.4×10 9/L and serum prolactin 37.42 μg/L. Ultrasonography of the right breast showed a 13.2 cm×11.0 cm×3.0 cm area low echo with unclear boundary, local fluidity, and abundant blood flow signals around. Granulomatous lobular mastitis of right breast (abscess stage) and hyperprolactiemia was diagnosed. After excluding physiological and pathological reasons, it was considered that risperidone caused hyperprolactinemia, which then induced granulomatous mastitis. However, risperidone could not be stopped without the guidance of a specialist, so only abscess incision, drainage, debridement, anti-infection, and anti-inflammatory were given. Purulent secretions gradually decreased, pain alleviated, and erythema of lower limbs partially subsided. Then risperidone dose was adjusted to 2 mg twice daily under the guidance of her psychiatrist. The serum prolactin level decreased (28.36 μg/L). At 1 year of follow-up, granulomatous mastitis did not recur.

A 19-year-old female patient received risperidone 3 mg twice daily for schizophrenia. She did not have nipple discharge before taking the drug. After taking the drug, nipple discharge occurred intermittently. One year later, a mass with pain in the right breast was found, which could not be alleviated after treatments with Rupi Sanjie capsules (乳癖散结胶囊), cefdinir, ibuprofen, rifampicin, and isoniazid and continued to increase, accompanied by bilateral knee pain, nodular erythema and tenderness of lower limbs. Laboratory tests showed white blood cell count 18.4×10 9/L and serum prolactin 37.42 μg/L. Ultrasonography of the right breast showed a 13.2 cm×11.0 cm×3.0 cm area low echo with unclear boundary, local fluidity, and abundant blood flow signals around. Granulomatous lobular mastitis of right breast (abscess stage) and hyperprolactiemia was diagnosed. After excluding physiological and pathological reasons, it was considered that risperidone caused hyperprolactinemia, which then induced granulomatous mastitis. However, risperidone could not be stopped without the guidance of a specialist, so only abscess incision, drainage, debridement, anti-infection, and anti-inflammatory were given. Purulent secretions gradually decreased, pain alleviated, and erythema of lower limbs partially subsided. Then risperidone dose was adjusted to 2 mg twice daily under the guidance of her psychiatrist. The serum prolactin level decreased (28.36 μg/L). At 1 year of follow-up, granulomatous mastitis did not recur.