A Rare Case of Myoid Hamartoma Masquerading As Invasive Breast Carcinoma

Introduction Breast Myoid Hamartoma is an extremely rare tumour. The incidence was reported as low as 0.7-5% of all benign breast tumours [1]. The pathophysiology of its development is not fully understood. However, with the current imaging and histopathological advances, we may be able to study in detail the behaviour and the curve of the disease. There are several variants of breast Myoid Hamartoma (MH) been described. The variants were determined by the cell types of the tumor, such as glandular or fibro adipose elements [2]. The Myoid variant, predominantly smooth muscle type of cells was seen. Clinically, breast MH is painless, soft to firm lump often with asymmetry. Breast Myoid Hamartoma (MH) is usually well circumscribed with capsule formation. Histologically, the lesion consists of admixtures of smooth muscle stroma, adipose tissue, hyaline cartilage with pseudoangiomatous hyperplasia. The mean age reported for breast MH is around 45 years old with postmenopausal females predominant. It is rarely seen in teenagers. Despite being a benign entity, breast Myoid Hamartoma (MH) has the ability for a malignant transformation and recurrence post excision. Hereby, we would like to report a case of an elderly lady that that was initially diagnosed with a malignant breast tumour that turned out to be a rare case of breast Myoid Hamartoma (MH) [3,4]. Case Report A case of a 64-years-old, elderly lady with underlying chronic idiopathic axonal polyneuropathy (CIAP), Diabetes type-2, and hypertension was referred to our centre for a right breast lump to rule out malignancy. The patient had been noticing a painless right breast lump with the size of a ‘golf ball’ for the past few months and claimed was increasing in size. Otherwise, the patient denies having any bloody nipple discharge, contralateral breast lump, constitutional symptoms nor family history of breast malignancy. Clinically, the breast is asymmetrical, inverted right nipple with ‘Peau-de-orange’ skin changes. There was a non-tender round mass palpable at the right upper-outer quadrant measuring (5x 5)cm in size, well-circumscribed, and has no fixity to the underlying structures. There were no obvious palpable bilateral axillary lymphadenopathies. Our initial diagnosis was right breast invasive carcinoma taking into account the patient’s age and clinical findings. The Patient was subjected to bilateral breast ultrasound on the same day. The right breast ultrasound showed a large ill-defined hypoechoic lesion at 9 o’clock position measuring (3.1 x 2.2) cm with peripheral vascularity and posterior shadowing effect. There was also multiple sub-centimetre right axillary lymph nodes noted with preserved fatty hilum and regular cortical thickness. A bilateral breast mammogram was arranged for the patient the following day. Mammogram findings of the right breast exhibit the presence of multiple suspicious groups of pleomorphic calcifications along with a localized dense fibrofatty tissue with BIRADS 4 category. Japan Journal of Clinical & Medical Research