No abstract

Objective: The Bethesda System for Reporting Thyroid Cytopathology (BSRTC) was introduced in thyroid cytology in 2007 and is now generally accepted. BSRTC categories include a morphologic description and risk of malignancy as well as follow-up suggestions in each group. However, the category entitled ‘atypia of undetermined significance or follicular lesion of undetermined significance' (AUS/FLUS) is problematic. This category is heterogeneous and has been overused so far. Study Design: Twenty-six studies were included in a meta-analysis. In addition to AUS/FLUS percentage, we analysed repeated AUS/FLUS percentage, cytological and histological correlations, and risk of malignancy and neoplasm for AUS/FLUS. Furthermore, stratification, inter- and intra-observer variability, and the possibility of a switch to another category and its clinical consequences were reviewed. Results: Out of a total of 81,833 cases, AUS/FLUS accounted for 10.9%, with a 34% risk of malignancy. Persistent AUS/FLUS was found in 21.6% in repeated cytology. Cytohistological correlation was analysed from 16 studies (4,964 cases), revealing 10.4% as AUS/FLUS and a 21.5% risk of malignancy. Conclusions: An AUS/FLUS category seems to be currently reasonable with clearly defined cytomorphological criteria which do not correspond unequivocally with those of the other categories. An AUS/FLUS category is justified and possible means of its improvement with immunohistochemistry, molecular analysis and imaging are discussed.

Warthin-like tumour is a rare variant of PC, occurring predominantly in elderly women. Its histological features are distinct and well recognizable, differentiating this tumour from a more aggressive tall-cell variant of PC. The apparent indolent behaviour seems to be consistent with the presence of dendritic/Langerhans cells and with low proliferative activity. A possible role of EBV in pathogenesis of this lesion was not proven. Further studies are necessary to determine the prognosis and metastatic potential of this neoplasm.

Three cases of nodular mucinosis of the breast are presented. They occurred in one male and two female patients. The patients had no signs of Carney's syndrome. All lesions were located under the nipple. They were poorly circumscribed and unencapsulated. They were soft and had a gelatinous consistency and white color. No patient had any evidence of recurrence or metastasis 6 months, 3 years and 6 years, respectively, after the surgical excision. The mucinous tissue consisted of acid mucopolysaccharides, which stained Alcian blue, Hale's colloidal iron positively, and they were periodic acid-Schiff (PAS) negative. Mucicarmine reaction was only faintly positive. The lesion should be distinguished particularly from mucocele-like lesions of the breast by the location, nodular arrangement, absence of accompanying ductal hyperplasia and staining properties of the mucous substances.

A retrospective study was made of 38 selected brest tumours with a poorly differentiated in situ duct component. These were classified on haematoxylin and eosin (H&E) as ductal carcinoma in situ (DCIS; 10 cases), DCIS with invasion (17 cases) and DCIS with features suggestive of for stromal invasion (11 cases). The last were these lesions composed of neoplastic ducts with irregular outlines and a myoepithelial layer that was not clearly evident or large neoplastic ducts growing close together or surrounded by inflammatory desmoplastic stroma. Cases of DCIS involving areas of sclerosing adenosis were included in this category. Consecutive sections obtained from each case were studied with a panel of antibodies against myoepithelial cells (alpha smooth muscle actin and calponin) and basal lamina (BL) components (laminin and type IV collagen). It was found that in situ lesions showed well-formed basal lamina and/or an evident myoepithelial layer. These features were lacking in the invasive areas. Nine of the 11 cases with suggestive features of stromal invasion were reclassified as invasive duct carcinoma (5 cases)and DCIS (4 cases), according to the absence or presence of a continuous myoepithelial layer and/or basal lamina. In 2 such cases immunohistochemistry yielded equivocal results and the label "suggestive of invasion" was therefore pertinent. Immunohistochemistry facilitates the diagnosis of breast DCIS; myoepithelial and basal lamina markers are useful in differentiating microinvasive from in situ ductal carcinomas of the breast.