Characterising benign fibrous soft-tissue tumours in adults: why is it so difficult and what do we need to know?

Fibrous, myofibroblastic, and fibrohistiocytic soft-tissue tumours are amongst the most common benign soft-tissue lesions encountered in clinical practice. They demonstrate varied biological behaviour and imaging characteristics. Benign fibroblastic lesions, such as nodular fasciitis, are small, have a self-limited course, and rarely recur after excision, whereas deep fibromatosis and plexiform fibrohistiocytic tumours tend to exhibit more aggressive features and often have high recurrence rates. MRI with its superior tissue contrast, multiplanar imaging capability, and lack of ionising radiation is regarded as the preferred method of tumour evaluation, tissue characterisation, and assessment of treatment response. Histopathological features are depicted at MRI, reflecting the amount and distribution of the cellular and fibrous matrix. Cellular tumours tend to show higher T2 signal intensity and post-contrast enhancement as compared to tumours with greater collagenous content, which appear dark and show less enhancement. Awareness of MR characteristics, pathological behaviour, and common sites of occurrence of fibrous soft-tissue tumours will help radiologists to determine the appropriate differential diagnosis and guide patient management.

MRI features of soft-tissue lumps and bumps.

Superficial soft-tissue lesions are frequently encountered by radiologists in everyday practice. Characterization of these soft-tissue lesions remains problematic, despite advances in imaging. By systematically using clinical history, anatomical location, and signal intensity characteristics on MRI images, one can determine the diagnosis for the subset of determinate lesions that have characteristic clinical and imaging features as well as narrow the differential diagnoses for lesions with non-specific or indeterminate characteristics. In this review, a spectrum of histologically proven benign and malignant superficial soft-tissue lesions from a single institution will be presented. In addition, a few tumour-like conditions will be included as they can be encountered during imaging of soft-tissue masses.

Nuclear morphometry in columnar cell lesions of the breast: is it useful?

AIMS: To evaluate the nuclear morphometric features of breast columnar cell lesions (CCLs) observed on mammotome core biopsies, to determine if there are significant measurable differences between those with atypia and those without. Correlation with follow-up open excision specimens was made. METHODS: Mammotome core biopsies performed on patients that contained CCLs were derived from the departmental case files. Histological material was reviewed and foci of CCLs demarcated for nuclear morphometric assessment, which was accomplished using an imaging system. Nuclear parameters studied were nuclear area and perimeter, circularity factor and feret's diameter. Statistical analysis used the GraphPad Prism software, with p<0.05 indicating significance. RESULTS: On examination of core biopsies of 40 patients with CCLs, 8 lesions were benign, 4 showed atypical lobular hyperplasia, 8 showed CCLs with nuclear atypia, 19 disclosed atypical ductal hyperplasia (ADH) and 1 showed ductal carcinoma in situ (DCIS). The nuclear area, perimeter and feret's diameter of CCLs with atypia were significantly greater than those without (p = 0.04, 0.03 and 0.019, respectively), whereas no difference was observed in the circularity factor. Follow-up open excision biopsy specimens in 24 patients showed upgrading to DCIS in 40% of cases diagnosed initially with ADH on core biopsy compared with 20% of CCLs with atypia. CONCLUSIONS: Nuclear morphometry in CCLs confirms nuclear size as the key parameter in the assessment of nuclear atypia. Whether it can be potentially used as an adjunctive tool depends on the establishment of appropriate cut-offs.

Pathological diagnosis of columnar cell lesions of the breast: are there issues of reproducibility?

AIMS: To assess inter/intraobserver variability in the interpretation of a series of digitised images of columnar cell lesions (CCLs) of the breast. METHODS: After a tutorial on breast CCL, 39 images were presented to seven staff pathologists, who were instructed to categorize the lesions as follows: 0, no columnar cell change (CCC) or ductal carcinoma in situ (DCIS); 1, CCC; 2, columnar cell hyperplasia; 3, CCC with architectural atypia; 4, CCC with cytological atypia; 5, DCIS. Concordance with the tutor's diagnosis and degree of agreement among pathologists for each image were determined. The same set of images was re-presented to the pathologists one week later, their diagnoses collated, and inter/intraobservor reproducibility and level of agreement for individual images analysed. RESULTS: Diagnostic reproducibility with the tutor ranged from moderate to substantial (kappa values, 0.439-0.697) in the first exercise. At repeat evaluation, intraobserver agreement was fair to perfect (kappa values, 0.271-0.832), whereas concordance with the tutor varied from fair to substantial (kappa values, 0.334-0.669). There was unanimous agreement on more images during the second exercise, mainly because of agreement on the diagnosis of DCIS. The lowest agreement was seen for CCC with cytological atypia. CONCLUSIONS: Interobserver and intraobserver agreement is good for DCIS, but more effort is needed to improve diagnostic consistency in the category of CCC with cytological atypia. Continued awareness and study of these lesions are necessary to enhance recognition and understanding.

Preoperative and intraoperative diagnosis of low-grade adenosquamous carcinoma of the breast: potential diagnostic pitfalls.

AIMS: Low-grade adenosquamous carcinoma (LGAC), a rare variant of metaplastic breast cancer, may mimic benign or other low-grade malignant lesions histologically. Diagnostic difficulty may be encountered when evaluating breast cytology, core needle biopsy or intraoperative frozen section specimens. METHODS AND RESULTS: Pathology reports, cytology aspirates and histological slides of LGAC diagnosed at the Department of Pathology, Singapore General Hospital, were reviewed. Four cases of LGAC were analysed. Cytology from the first case showed atypical cells and the subsequent surgical excision specimen showed a complex sclerosing lesion with LGAC. The second and third cases were investigated by core needle biopsies: the preoperative histological features were suggestive of but not diagnostic of LGAC, until further excision biopsies were performed. The fourth case entailed a frozen section specimen, for which definitive diagnosis was deferred to paraffins. The patients remained well with no evidence of recurrent disease to date. CONCLUSIONS: When limited material, in the form of needle aspirates, core biopsy specimens or frozen sections, is submitted for histology, making a diagnosis of LGAC is not only challenging, but may be impossible. In difficult cases, careful pathological assessment, clinicopathological correlation and follow-up or complete excision biopsy may prove invaluable in establishing a definitive diagnosis.