Cutaneous Metastasis from Breast Tumour Seeding in Percutaneous Needle Biopsy.

tissues. 0.7–0.9% of patients with a malignant tumour at any site can develop a cutaneous or subcutaneous metastasis after percutaneous procedures [2]. The duration between the onset of tumour seeding and the previous percutaneous needle biopsy has been shown to vary widely. Clinically, tumour deposits are observed as painful cutaneous or subcutaneous nodules, typically round or oval, with well-defined margins, and are reddish, angiomatous or normal skin coloured. In our patient, the lesion was firm and painless, normal skin colour with irregular margins and mimicked a keloid scar. Generally, histological and immunohistochemical markers for tumour seeding are similar to the primary tumour, as in our case. PNB of lymph node within the neck region, axilla and groin are commonly performed. The potential adverse events of lymph node surgery include lymphedema, numbness, tingling, pain at the site of surgery and difficulty moving the affected body part. Tumour seeding following lymph nodes biopsy, such in this case, is an unusual occurrence. Typically, patients with a history of breast cancer report a tumour seeding directly on the breast region, after a PNB on the primary tumour. Needle tract seeding of malignant cells is detected in 22% of such patients [1]. In a recently study, a statistically significant difference between seeding occurrence for invasive ductal carcinoma and invasive lobular carcinoma, with rates of 40% and 15%, respectively, was found [1]. This current case is an unusual presentation of tumour seeding from an invasive ductal carcinoma because the initial tumour was breast cancer lymph node metastases. Any suspicious skin lesion appearing at the site of a PNB must be considered carefully and subjected to cutaneous biopsy to exclude the diagnosis of malignancy.