Lactating Adenoma Co-Existing with High Grade Invasive Ductal Carcinoma: Collision Tumour or Mere Co-Incidence

Abstract

Adoke Kasimu Umar and James O Enemari

Background: Lactating adenoma are benign lesions that can presents as a solitary or multiple freely movable breast mass during pregnancy or puerperium. The lesion is actually a localized focus of hyperplasia in the lactating breast, which may also develop in ectopic locations such as the axilla, chest wall, or vulva. Breast cancer developing during pregnancy or puerperium is known as pregnancy associated breast cancer. We report a case of lactating adenoma co-existing with high grade invasive ductal carcinoma in young patient in puerperium with a positive family history of breast cancer. We present a 19-year-old female with a palpable mass on her right upper outer quadrant of her right breast measuring 5x4x2cm with ipsilateral supraclavicular lymph node enlargement. Cytomorphology of the lesion showed tumour cells arranged in nests and solid sheets with abundant fibromyxoid stroma. Also seen are abnormal mitosis and areas of lymphovascular invasion. Proliferating glands are seen lined by cuboidal cells with cytoplasmic vacuolations. Immunohistochemical stain show tumour cells were triple negative (negative for progesterone receptor (PR), estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) and strongly positive for EMA in both tumours.

Conclusion: This study indicated that lactating adenoma can co-exist with high grade invasive ductal carcinoma in a young patient in puerperium. The fact that this patient has a positive family history of breast cancer in first degree relative may explain the presentation at a very young age. It may be very difficult to ascertain whether this is a collision tumour or a mere co-incidence of lactating adenoma with breast cancer in this patient.

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