Spiculated Masses

The mammographic appearance of a spiculated mass is characterized by an isodense to hyperdense central lesion with thin, sharp lines radiating from its margin. The spicules can range from a few millimeters to several centimeters in length. In malignant lesions the spicules on histology represent tumor cells in desmoplastic stroma extending into adjacent fibroadipose tissue. This may result in architectural distortion seen in association with the spiculated mass. Although a spiculated mass is frequently thought of as a quintessentially classic finding for malignancy, most commonly an invasive ductal carcinoma (IDC), benign entities such as fat necrosis, pseudoangiomatous stromal hyperplasia, and sclerosing adenosis, may also have a spiculated appearance and may mimic malignancies. Other benign entities include sclerosing adenosis, diabetic mastopathy, and infectious etiologies. Granular cell tumors which are rarely seen in breast can also present as spiculated masses. Correlation of imaging findings with clinical and surgical history is important, however, a core needle biopsy is usually necessary to exclude malignancy when a spiculated mass is detected on imaging. Invasive ductal carcinoma, NST (no special type) the most common type of breast cancer presents as a hyperdense spiculated mass with associated pleomorphic calcifications when accompanied by ductal carcinoma in situ (DCIS) (Freer et al. Radiology 275(2):377-383, 2015). The invasive tumor cells elicit a desmoplastic stromal response in the surrounding tissue which may be seen as an echogenic halo. Invasive lobular carcinoma, which accounts for 10-15% of invasive mammary carcinomas, can have a variable appearance on mammography and is a common cause for false-negative mammogram (Kuba et al. Mod Pathol 2021, published online; WHO Classification of Tumors Editorial Board. Breast tumours. WHO classification of tumors. Lyon: IARC; 2019). However with tomosynthesis, invasive lobular carcinomas are more easily detected than in the past. Invasive lobular carcinomas are commonly multifocal, multicentric, and bilateral compared to invasive ductal carcinoma, NST. On histologic examination diffuse infiltration of discohesive tumor cells in a single file pattern is visualized. Tubular carcinoma and mucinous carcinomas are well-differentiated invasive cancers with a good prognosis that can present as a hyperdense or isodense spiculated mass on mammogram.