Architectural Distortions

Architectural distortion on mammography presents as thin, radially arranged spicules originating from a central point without a definite associated mass lesion. When the lesion is located close to the edge of the glandular parenchyma, at the subcutaneous or prepectoral fat/ fibroglandular breast tissue interface, a focal retraction of the glandular tissue edge may be seen. Tomosynthesis has increased the detection of architectural distortions by about 50% when compared to full field digital mammography (Ray et al. Breast J. 21(5):538–42, 2015; Partyka et al. AJR Am J Roentgenol. 203(1):216–22, 2014). An ultrasound correlate, when present, may appear as a distortion with vague posterior shadowing. On MRI, architectural distortion is best visualized on T1WI, and an associated enhancement may be detected on post-contrast images. In the absence of enhancement, the likelihood of malignancy is 2% (Niell et al. AJR Am J Roentgenol. 211(5):1171–8, 2018). Although the absence of a sonographic correlate decreases the likelihood of malignancy by about 40%, there is still a nearly 30% chance of malignancy if an architectural distortion is seen on tomosynthesis only (Alshafeiy et al. Radiology. 288(1):38–46. 2018; Patel et al. AJR Am J Roentgenol. 210(6):1395–1400, 2018). For architectural distortion seen on 2D imaging, the likelihood of malignancy may be as high as 74% (Alshafeiy et al. Radiology. 288(1):38–46. 2018). Correlation with patient history of prior breast surgery is crucial; location of scars on the skin must be correlated with findings on mammography. The differential diagnosis for architectural distortions in the absence of a surgical scar includes benign entities: radial scar/complex sclerosing lesion, sclerosing adenosis, focal fibrosis, and malignant entities: invasive ductal carcinoma, tubular carcinoma, invasive lobular carcinoma, and ductal carcinoma in situ (Vijapura et al. AJR Am J Roentgenol. 211(6):1397–1404, 2018). Radial sclerosing lesions are benign lesions that are characterized by a central fibrotic nidus with hyalinized fibroelastotic stroma and surrounded by varying degrees of proliferative changes that can mimic invasive carcinoma on imaging and histology. The term complex sclerosing lesion is used for larger lesions greater than 1 cm. The majority of radial scars are incidental microscopic findings, but larger lesions can present as a palpable mass. Tubular carcinomas mimic radial sclerosing lesions on mammography, macroscopic examination and on histology. However, the presence of a myoepithelial layer around entrapped glands in radial sclerosing lesions helps in distinguishing them from tubular carcinoma which lacks a myoepithelial cell layer. Immunohistochemical stains can be employed in difficult cases. Invasive lobular carcinoma can rarely present as architectural distortion on imaging. Among the special carcinomas, invasive lobular carcinomas are the most common malignancies and can present as architectural distortion. Invasive lobular carcinoma is characterized by a diffuse infiltration in the breast of discohesive cells in a single file pattern (Schmitt and Collins. Biopsy interpretation of the breast. third edition, Wolters Kluwer Health, 2018). Other benign entities that present as architectural distortion include fat necrosis, postsurgical scars from prior reduction mammoplasty, prior biopsies, and lumpectomies.