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The umbilicus is a rare site for malignant melanoma. We report two cases of umbilical melanoma and analyse the mechanisms of diffusion of the neoplasm in relationship to the arterial, venous, and lymphatic anatomy of the region. Because of the peculiarity of these connections, we propose a revision of the concept of melanoma stage for the umbilical region. [ABSTRACT FROM AUTHOR]

Microfollicular nodular lesions of the thyroid gland may represent a differential diagnosis problem. Firstly, nodular areas of follicular hyperplasia have to be distinguished from follicular adenomas. On the other hand, nodular microfollicular areas exhibiting large pale nuclei, occasionally found in hyperplastic nodules and follicular adenomas, must be discriminated from latent papillary carcinomas with predominant follicular architecture. The diagnosis of follicular carcinoma still requires the detection of vascular and/or capsular microinvasion. A more refined study was planned to search for additional descriptors useful for diagnosis The authors report the results of an ultrastructural investigation carried out on 220 thyroid nodular lesions and 50 specimens of macroscopically nonnodular glands. An infolding arrangements of the thyreocyte basal border(TBB)and follicular basement membrane(FBM)was demonstrated in 50/50 nonnodular thyroid tissue specimens and 53/67(79.1%)hyperplastic nodular lesions(p < .005). A linear arrangement of the TBB and FBM was found in 85/121(70.2%)follicular adenomas and in 32/32 differentiated carcinomas(p < .001). In the last group, 12/32(37.5%)cases showed focal discontinuities of FBM. In conclusion, the benign thyroid nodules show a prevalently infolding arrangements of TBBs, whereas the majority of proliferative lesions display a linear morphology. In absence of an infiltrating pattern there is no morphological evidence of discriminating potentially malignant vs. benign lesions. The linear distribution of TBBs and FBMs places the case in a group of borderline lesions that involve a more careful postsurgery investigation. [ABSTRACT FROM AUTHOR]