BACKGROUND Breast trauma can always have diagnostic pitfalls. In the presence of a recurrent hemorrhagic cysts, cancer should always be suspected. CASE REPORT A 59-year-old woman noted a palpable mass after breast trauma from falling at home. Radiological exams showed a breast cyst with well-defined margins, with corpuscular and dense fluid components. First, a conservative approach was implemented. One week later, a fine-needle aspiration cytology (FNAC) of the mass showed bloody fluid without atypical cells. Three weeks later, the patient was emergently evaluated due to increased size of the lesion and anemia. To avoid further blood loss and due to suspected malignancy, an urgent surgical excision biopsy was planned. Histopathology revealed a poorly-differentiated carcinoma and the patient was treated with left modified radical mastectomy with axillary dissection. Adjuvant chemotherapy was administered. At 6-month follow-up, the patient was free from recurrences. CONCLUSIONS Recurrent hemorrhagic cysts should always be investigated and considered as a possible cancer lesion. Sonography and cytological exam are the first steps in case of suspicious cysts, but false-negative results are common. In such cases, resection of the cyst should be considered. Immediate resection is valid in cases of diagnostic uncertainty or inability to assess the cyst with imaging or biopsy.