Primary non-Hodgkin's lymphoma of breast with scalp involvement in follow-up--an uncommon presentation.

Primary non-Hodgkin's lymphoma of the breast is a rare tumour accounting for 0.04 to 0.5% of all malignant breast tumours. The aim of this case presentation is to report such rare entity with an uncommon presentation. A 48-year female presented with rapidly growing firm mass in right breast (upper outer quadrant) and fine needle aspiration cytology (FNAC) was performed for clinical suspicion of breast carcinoma. Cytological examination of smears showed large cells arranged discretely, though occasional small clusters were also seen. The cells had high nuclear-cytoplasm (N-C) ratio and prominent nucleoli. Based on cytomorphology, differential diagnoses of high grade non-Hodgkin's lymphoma and poorly differentiated carcinoma was made. A tru-cut biopsy was suggested for confirmation. Histologic examination revealed diffuse large cells (monomorphic type) with prominent nucleoli.The tumour cells were reactive for CD45, CD20, and negative for cytokeratin, CD30, CD3 and CD5. A histopathologic diagnosis of non-Hodgkin's lymphoma of diffuse large B cell lymphoma type was confirmed. The patient was treated with combined chemotherapy and radiotherapy. After one year, the patient developed a swelling in the scalp and proved to be diffuse large B cell lymphoma by tru-cut biopsy. Now, the patient was treated with chemotherapy alone. Two-year follow-up of the case was uneventful. Since FNAC is initial diagnostic tool for breast lesions, a differential diagnosis of breast lymphoma should always be kept in mind, especially in poorly differentiated malignant tumours. Such cases need to be confirmed by histopathology and immunohistochemistry.