Case number:	037
Age:	50
Clinical presentation:	Postmenopausal woman with average risk of developing breast cancer presented with a left breast lump noticed 6 months ago. This was associated with pain at the site. Examination revealed a tender firm mobile lump less than a centimetre in diameter in the upper outer quadrant of the left breast.

Mammography:

Breast composition:	ACR category b (there are scattered areas of fibroglandular density)
Mammography features:

‣ Location of the lesion:	Left breast, upper outer quadrant at 3 o’clock, anterior and middle thirds
‣ Mass:
• Number:	1
• Size:	1.5 × 1.0 cm
• Shape:	Irregular
• Margins:	Microlobulated
• Density:	Equal
‣ Calcifications:
• Typically benign:	None
• Suspicious:	None
• Distribution:	None
‣ Architectural distortion:	None
‣ Asymmetry:	None
‣ Intramammary node:	None
‣ Skin lesion:	None
‣ Solitary dilated duct:	None
‣ Associated features:	None

Ultrasound:

Ultrasound features: Left breast, upper outer quadrant at 3 o’clock

‣ Mass
• Location:	Left breast, upper outer quadrant at 3 o’clock
• Number:	1
• Size:	1.0 cm in greatest dimension
• Shape:	Irregular
• Orientation:	Not parallel
• Margins:	Microlobulated
• Echo pattern:	Hypoechoic
• Posterior features:	No posterior features
‣ Calcifications:	None
‣ Associated features:	Internal vascularity
‣ Special cases:	None

BI-RADS:

BI-RADS Category: 4B (moderate suspicion of malignancy)

Further assessment:

Further assessment advised: Referral for cytology and for excision biopsy

Cytology:

Cytology features:

‣ Type of sample:	FNAC
‣ Site of biopsy:
• Laterality:	Left
• Quadrant:	Outer lower
• Localization technique:	Palpation, rubbery consistency felt through the needle
• Nature of aspirate:	whitish
‣ Cytological description:	Cellular smear showing elongated, branching epithelial fragments of regularly arranged cohesive cells. Single, bare bipolar or oval nuclei are scattered in the background. Loose fibromyxoid stroma are also seen
‣ Reporting category:	Benign
‣ Diagnosis:	Fibroadenoma
‣ Comments:	None

Histopathology:

Lumpectomy

Histopathology features:

‣ Specimen type:	Lumpectomy
‣ Laterality:	Left
‣ Macroscopy:	Lumpectomy specimen (9.0 × 7.0 × 3.0 cm) with skin flap. Cut surface shows a firm white area (1.2 × 1.0 × 0.5 cm), 1.0 cm from the inferior margin below the skin. Another whitish area (3.0 × 2.0 cm) is seen superomedially
‣ Histological type:	Sections from lumpectomy specimen reveal histological features of a fibroadenoma having intracanalicular and pericanalicular patterns. A few ducts in the fibroadenoma show features of UDH. The overlying skin is unremarkable. The adjacent fibroadipose tissue shows foci of fibrosis
‣ Histological grade:
‣ Mitosis:
‣ Maximum invasive tumour size:
‣ Lymph node status:
‣ Peritumoural lymphovascular invasion:
‣ DCIS/EIC:
‣ Margins:
‣ Pathological stage:
‣ Biomarkers:
‣ Comments:

Case summary:

Postmenopausal woman presented with left breast lump. Diagnosed as mass of suspicious morphology, BI-RADS 4B on imaging and as fibroadenoma left breast on cytology. Fibroadenoma showed foci of epithelial hyperplasia on histopathology.

Learning points:

Fibroadenoma can reveal atypical features on ultrasound suspicious of breast carcinoma, such as irregular shape, heteroechogenicity, microcalcifications within the mass, or posterior shadowing. Microlobulated margins are a feature of atypical fibroadenoma. These atypical appearances are caused by interdigitation of the surrounding parenchyma.