Suspicious of Malignancy

This chapter defines the Suspicious of Malignancy category, discusses the reasons why suspicious of malignancy reports occur, and why a definitive diagnosis of malignancy cannot or should not be made in certain circumstances. The category allows for the maintenance of a high positive predictive value of a malignant diagnosis. Many of the reasons for an inability to make a definitive diagnosis of malignancy are similar to those seen in the atypical category and include the specimen quality, which is largely reliant on the skill of the FNAB operator, the experience of the cytopathologist interpreting the smears, and the inherent nature of the lesion. There are overlapping cytological criteria between some breast proliferative and in situ lesions, and between in situ lesions and some malignant tumours, and distinguishing carcinoma and lymphoma also may be difficult on occasion. The chapter details the cytological features of low-grade ductal carcinoma in situ (DCIS), and discusses this controversial area to provide an approach to the diagnosis and differential diagnoses for low-grade DCIS. The management of Suspicious of Malignancy FNAB cytology cases is presented and highlights the need for further investigation by core needle or excision biopsy in all cases. Sample reports are presented.