Squamous metaplasia of lactiferous ducts (SMOLD).

The aim of this review is to illustrate the mammographic and sonographic appearances of squamous metaplasia of the lactiferous ducts (SMOLD) and to discuss the disease processes of this uncommon breast disease, which shows a strong correlation with smoking. The most common mammographic appearance is of a retro-areolar asymmetrical density. Ultrasonography of the symptomatic breast typically shows a retro-areolar, predominately medial, ill-defined, hypoechoic lesion with either abscess or sinus/fistula formation. Duct dilatation and continuity with lactiferous ducts is commonly seen. Increased vascularity is occasionally seen on colour Doppler ultrasound. Pathology tissue confirmation is always required and this can be by histology of a core biopsy or excision specimen, or fine-needle aspiration (FNA) cytology. Occasionally smears of an associated abundant nipple or sinus discharge may be of value.