Role of BRAF molecular analysis in the management of papillary thyroid carcinoma: analysis of cytological and histological samples.

BACKGROUND: Although fine needle aspiration (FNA) is the standard diagnostic test for the characterization of a suspicious thyroid nodule, in some cases cytological evaluation is inconclusive. The aim of this study was to determine the role of BRAF mutation in aiding diagnosis and to verify whether archival cytological samples could be suitable for molecular analysis. METHODS: Eighty-five patients with suspicious (Thy4) or follicular (Thy3) lesions on cytology were resubmitted to a second FNA for BRAF mutation analysis. Of these, 56 subsequently underwent surgery. The usefulness of archival samples for molecular analysis was also studied in a second cohort of 42 patients with a confirmed diagnosis of papillary thyroid carcinoma for whom both archived paraffin-embedded histological samples and cytological smears were available. A further 15 patients with paired fresh FNA and archived cytological and histological samples were recruited. RESULTS: BRAF mutation was found in the fresh FNA samples from 10 of 56 patients who had surgery with previous inconclusive cytology (4/45, 9%, Thy3 and 6/11, 55%, Thy4). The BRAF test showed a specificity and positive predictive value of 100% (26/26 and 10/10, respectively), sensitivity of 33% (10/30) and negative predictive value of 57% (26/46). There was absolute concordance between the BRAF results obtained with 42 histological and cytological archived samples. BRAF analysis on 15 archived cytological samples showed absolute concordance with histology, whereas there was one false negative on the matched fresh FNA. CONCLUSION: BRAF analysis is a highly specific test that can facilitate cytological diagnosis in some cases and can also be performed on archived cytological samples.

Fourier transform infrared microscopy identification of crystal deposits in tissues: clinical importance in various pathologies.

The presence of crystal deposits in tissues is associated with various pathologies. Sometimes their identification is useful for understanding the etiology or the mechanism of the disorder. The authors applied Fourier transform infrared microscopy (FTIRM) to the molecular characterization of crystal deposits in tissue and compared the results with those provided by histologic studies using polarized light microscope and histochemical reactions. Twenty-five biopsies were investigated. In 10 cases, the results were in good agreement. In 15 cases only FTIRM could precisely identify the crystals. In three cases, this technique allowed to characterize dihydroxyadenine crystals revealing an adenine phosphoribosyltransferase deficiency previously undiagnosed in patients presenting severe chronic renal failure. In three cases, crystal deposition was related to drug therapy. In other cases, crystal identification was useful to understand the mechanism of the pathology responsible for tissue damage and crystal deposition.

Investigation of urinary crystals by Fourier transform infrared microscopy.

Although crystalluria is generally considered a normal finding, sometimes it gives evidence of renal disturbance. Thus, detection and identification of urinary crystals may provide useful data for understanding the etiology of mechanism of the disorder. Light microscopy may be not sufficient to accurately identify the crystals. We investigated the ability of Fourier transform infrared microscopy (FTIRM) to identify isolated crystals of clinical interest. Twenty-five urine samples presenting crystalluria were tested because of their unusual aspect. We successfully identified 16 compounds and showed that crystals with the same apparent morphology can be composed of different substances. Moreover, an unexpected structure may be an insoluble phase of a drug metabolite. We conclude that FTIRM is a good technique for investigating urinary crystals of clinical interest.