Teaching Case

A 48-year-old female patient presented with long standing left breast lump which was suddenly increasing in size. She had no significant family history. Clinical examination revealed a large lobulated partly cystic and partly solid lump occupying outer half of left breast causing external contour bulge.

Patient refused mammography so ultrasonography was performed directly which revealed a large cystic solid lesion occupying 2-6 o’clock periareolar region of outer half of left breast with marked internal vascularity of the solid component. Cystic component revealed bright echoes (likely due to blood). Adjacent to the lesion, there was another irregular mass appearing in continuity with solid component.
Contrast-enhanced MRI revealed large intracystic mass showing extension as multiple nodules in the adjoining parenchyma. The overall abnormality measured 7.5 x 4.8 cm. The solid component measured 45 x 45 mm and revealed type III curves with minimally low ADC values (1.18 × 10-3 mm2/sec). Cystic component revealed blood products with fluid debris levels. Lesion was assigned BI RADS 4c category.
Ultrasound guided core needle biopsy of the lesion revealed fibroadenoma. Patient underwent left wide local excision for the left breast lesion since clinicoradiological and pathological findings were discordant.

Phylloides tumour is a rare fibroepithelial neoplasm accounting for less than 1% of all breast tumours presenting with a clinically benign lump, which may be rapidly growing [1].
The median age at the time of diagnosis is 45 years. However, it can occur in young adults and adolescents therefore the diagnosis cannot be excluded on basis of age. Many phylloides tumours are large, but others measure less than 5 cms in diameter. [2]
Histologically, it is composed of extremely cellular stroma, accompanied by the proliferation of benign ductal structures. They typically exhibit enhanced intracanalicular growth pattern with leaf like projections into the dilated lumina [3].

Phylloides tumour is classified as benign and low or high grade malignant reflecting an estimate of probable clinical course based on histological appearance. Benign, borderline and malignant type show mitosis (per 10 HPF) of 5, 5–9 and 10 or greater respectively. Our case revealed mitotic activity of 5-6/10 HPF. Benign will not metastatise and have low probability for local recurrence after excision. A low grade malignant or borderline tumour has a slight probability (<5%) of metastasis, but such a tumour is more likely than a benign phylloides to recur locally. Metastasis occurs in about 25% of high grade malignant lesions and are prone to local recurrence. High grade malignant show earlier recurrences than after initial treatment of benign or low grade malignant tumours. Less than 1% high grade tumours give rise to axillary lymph node metastasis [4].

Larger tumours frequently contain clefts or cystic cavities [5], however, the tumour rarely shows morphologically intracystic growth. In this case, the tumour had enlarged so rapidly that haemorrhage had occured in the intracanalicular lumen, making cystic portion as the predominant component with fluid and leaf-like papillary protrusions of stromal connective tissues extending to cystic areas giving intracystic mass type appearance.

Only few similar cases have been reported in literature so far. Two separate reports of intracystic phylloides tumour, both borderline cases were described by Horiguchi et al [6] and shintaro et al [7].

Surgical excision with wide tumour-free margins (atleast 10 mm) is mainstay of management [8].Preoperative diagnosis of phylloides tumour is important for appropriate surgical planning, avoiding chances of reoperation because of inadequate excision.

Although the common imaging feature is a mass with circumscribed or lobulated margins with possible cleft like cystic spaces, the presence of intracystic mass on sonography and MRI in a clinically palpable rapidly enlarging lump should include the differential of phylloides tumour.