Collagen Profiles and Architectural Analyses of the Stromal-Capsular Components of Thyroid Neoplasms Correlating with Their Invasive Capabilities and Differential Diagnosis

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The main stream of this research constitutes following two summaries : one focusing on the reassessment of diagnostic approaches on follicular neoplasms and proposing a new technique for a histoarchitectual examination ; and another clarifying the collagen profiles of stroma and capsule associated in thyroidal tumors.Fourteen encapsulated follicular neoplasms were extensively dissected without tangential sectioning to represent tHe circumference of the entire capsule on sequential histologic sections. A thorough evaluation of these sections divided the 14 cases into five benign adenomas, seven encapsulated carcinomas with only intracapsular angioinvasion, and two minimally invasive carcinomas with focal capsular invasion.Among these nine early-stage follicular carcinomas it was found that angioinvasion occurred multicentrically in at least seven and showed a geographically even distribution. Angioinvasion was found far more often than capsular invasion on the circumference of all nine … More early-stage carcinomas. Multiple sections produced by this extensive dissection aided the disclosure of minute but convincing findings of angioinvasion. Also, a fibrous capsule ds thick as 3.8 mm at maximum as well as an irregular interface between the capsule and parenchyna were often found to be characteristic in these early-stage carcinomas. Thus, upon comparison with 38 previous cases of similarly localized follicular. neoplasms in wlilch randomly sampled histologic sections yielded diagnoses of benign adenoma (21 cases) and encapsulated or minimally invasive carcinoma (17 cases), extensive circumferential evaluation of the capsule is considered to allow not only effective distinction of follicular neoplasm with slight invasive capability from benign adenoma but also adequate assessment of invasive foci with application of strictcriteria. Despite the similarity of clirilcal prognosis between all the above adenomas and early-stage carcinomous, given the limited followup period, an extensive examination method introduced herein is practically useful and necessary for identification of malignancy in encapsulated follicular neoplasms.Furthermore, the immunophenotypes of 13 follicular neoplasms (five adenoma and eight minimally invasive carcinoma) and 27 papillary carcinomas have been characterized focusing their fibrous capsule or capsule-like stroma with antibodies against elastin and several types of collagen peptide. The findings were reinforced with conventional histologic stains and ultrastructure. An abundant lamellar distribution of basal lamina-like substances and elastin was found characteristic in the capsule of follicular neoplasms, most pronounced in adenoma, and appearing focally or in zones in invasive carcinoma. In the capsule-like stroma of papillary carcinoma, such findings were totally lacking ; instead, similar to the zones lacking elastin in the fibrous capsule of some follicular carcinomas, diffuse deposits of type I and III collagen prevailed. The capsule, an exclusive feature of follicular neoplasms, is considered to result from accumulation of compressed paraneoplastic interstitial constituents in addition to a possible host reaction against the expansile growth, whereas the increase of fibrous tissues reactive for types I and III collagen showing either a capsule-like architecture or within the interstitium is considered to be a stromal reaction related to the invasive growth in papillary carcinoma and some earlv follicular carcinomas. Less