Case number:	065
Age:	60
Clinical presentation:	Postmenopausal woman with average risk of developing breast cancer presented with painless right breast lump. On examination, a hard non-tender lump was found in the right breast.

Mammography:

Breast composition:	ACR category a (the breasts are almost entirely fatty)
Mammography features:

‣ Location of the lesion:	Right breast, upper outer quadrant at 10 o’clock, middle third
‣ Mass:
• Number:	1
• Size:	3.1 × 2.2 cm
• Shape:	Oval
• Margins:	Partly circumscribed and partly indistinct
• Density:	High
‣ 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: Right breast, upper outer quadrant at 10 ’o’clock

‣ Mass
• Location:	Right breast, upper outer quadrant at 10 ’o’clock
• Number:	1
• Size:	3.0 × 1.4 cm
• Shape:	Irregular
• Orientation:	Parallel
• Margins:	Partly circumscribed and partly indistinct margins
• Echo pattern:	Hypoechoic
• Posterior features:	Posterior shadowing
‣ 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

Cytology:

Cytology features:

‣ Type of sample:	FNAC (solid lesion)
‣ Site of biopsy:
• Laterality:	Right
• Quadrant:
• Localization technique:	Palpation
• Nature of aspirate:	Mucoid
‣ Cytological description:	Smears show malignant cells with a uniform regular nucleus; many cells are plasmacytoid with eccentric nuclei. Background shows mucinous material
‣ Reporting category:	Malignant
‣ Diagnosis:	Carcinoma
‣ Comments:	None

Histopathology:

MRM

Histopathology features:

‣ Specimen type:	MRM
‣ Laterality:	Right
‣ Macroscopy:	Cut section shows a well-circumscribed greyish white tumour (2.2 × 2.0 × 1.5 cm), with mucinous areas of soft consistency
‣ Histological type:	Mucinous
‣ Histological grade:	Grade 1 (3 + 1 + 1 = 5)
‣ Mitosis:	Not identified
‣ Maximum invasive tumour size:	2.2 cm in greatest dimension
‣ Lymph node status:	0/22
‣ Peritumoural lymphovascular invasion:	Not identified
‣ DCIS/EIC:	Not identified
‣ Margins:	Free of tumour
‣ Pathological stage:	pT2N0
‣ Biomarkers:
‣ Comments:

Case summary:

Postmenopausal woman presented with lump in the right breast. Diagnosed as right breast mass of suspicious morphology, BI-RADS 4B on imaging, as mucinous carcinoma on cytology, and as mucinous carcinoma, pT2N0 on histopathology.

Learning points:

Mucinous carcinoma is a subtype of breast carcinoma most commonly seen in women older than 60 years. It is characterized by the presence of extracellular mucin. Mammography shows a mass with partly circumscribed and partly indistinct margins. Ultrasound shows posterior acoustic enhancement in more than 50% of cases.