Case number:	095
Age:	58
Clinical presentation:	Postmenopausal woman with average risk of developing breast cancer presented with a lump in the left breast. Examination revealed a 1.5 cm lump in the retroareolar region of the left breast.

Mammography:

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

‣ Location of the lesion:	Left breast, central portion of the breast, central zone, anterior third
‣ Mass:
• Number:	1
• Size:	1.2 × 0.9 cm
• Shape:	Irregular
• Margins:	Indistinct
• 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, central portion of the breast

‣ Mass
• Location:	Left breast, central portion of the breast
• Number:	1
• Size:	1.2 × 0.8 cm
• Shape:	Irregular
• Orientation:	Not parallel
• Margins:	Indistinct
• Echo pattern:	Heteroechoic
• Posterior features:	No posterior features
‣ Calcifications:	None
‣ Associated features:	Vessels in rim
‣ Special cases:	None

BI-RADS:

BI-RADS Category: 4A (low level of suspicion for malignancy)

Further assessment:

Further assessment advised: Referral for cytology

Cytology:

Cytology features:

‣ Type of sample:	FNAC (solid lesion)
‣ Site of biopsy:
• Laterality:	Left
• Quadrant:	Retroareolar lump
• Localization technique:	Palpation
• Nature of aspirate:	0.2 mL of thick whitish material
‣ Cytological description:	Smear shows many neutrophils and foamy macrophages. Epithelioid histiocytes are seen in large conglomerates
‣ Reporting category:	Benign
‣ Diagnosis:	Granulomatous inflammation
‣ Comments:	None

Histopathology:

Breast lumpectomy

Histopathology features:

‣ Specimen type:	Breast lumpectomy
‣ Laterality:	Left
‣ Macroscopy:	Cut surfaces of the serial sections do not show any tumour nodules. Soft whitish areas are noted in the adipose tissue
‣ Histological type:	Section shows granulomatous mastitis with epithelioid cell conglomerates, Langhans giant cells, and peripheral cuff of lymphocytes. Some dilated ducts with inspissated secretions and surrounded by chronic inflammation are seen
‣ Histological grade:
‣ Mitosis:
‣ Maximum invasive tumour size:
‣ Lymph node status:
‣ Peritumoural lymphovascular invasion:
‣ DCIS/EIC:
‣ Margins:
‣ Pathological stage:
‣ Biomarkers:
‣ Comments:	Negative for acid-fast bacilli

Case summary:

Postmenopausal woman presented with left breast lump. Diagnosed as left breast subareolar tubular irregular lesion, BI-RADS 4A on imaging and as granulomatous mastitis on cytology and histopathology.

Learning points:

Idiopathic granulomatous mastitis is characterized by the presence of non-necrotizing granulomas confined to the breast lobules, in which no microorganisms are identified.
Periductal mastitis may represent a localized response to stagnant secretions. It may produce retraction or inversion of the nipple.
Diagnosis of granulomatous mastitis is difficult on clinical findings of subacute or relapsing inflammation with discharging cutaneous sinuses and imaging alone. The morphological features on mammography include architectural distortion, breast oedema, skin thickening, and axillary reactive nodes; all of these mimic malignancy. Multiple hypoechoic areas with varying degree of necrosis and increased peripheral vascularity are seen on ultrasound. Biopsy confirms the diagnosis and excludes malignancy.