title: [Unusual non-neoplastic lesions in the "surgical pathology" of the thyroid].
abstract: This review aims to describe and assist in the categorization of most of the unusual non-neoplastic conditions, encountered in the surgical pathology of the thyroid. The conditions included are: normal intrathyroidal vestigial tissues/structures (i.e. rests of the ultimobranchial body and thyroglossal duct) and their relevant pathological derivatives (ultimobranchial body cyst, intrathyroidal lymphoepithelial cyst, thyroglossal duct cyst); mature intrathyroidal heterologous tissues/organs of either metaplastic or heterotopic origin (adipose tissue, striated skeletal muscle, cartilage, parathyroid glands, thymus, salivary gland tissue) and their relevant pseudotumoural lesions; varieties of metaplastic and non-metaplastic morphologic changes of the thyroid follicular epithelium (oncocytic, clear cell/signet ring cell, darkly pigmented cell, mucinous (myxoid), squamous, spindle cell); amyloid goiter; some reactive and/or degenerative cytologic and nuclear atypicalities (nuclear pseudoclearing and cell pleomorphism) as well as some hyperplastic or peculiar growth patterns (capsular pseudoinvasion; vascular invasion; papillary carcinoma-like and paraganglioma-like patterns) of benign conditions mimicking neoplasia; and finally. some pseudotumoural lesions of the stroma (pseudoangiosarcomatous vascular proliferation, and post-fine-needle aspiration spindle cell nodule). The pathogenetic mechanism, the morphologic interpretation, and the differential diagnosis of each of the above-listed conditions are discussed and pertinent illustrations for many of them are also provided. Lesions of thyroid tissue situated outside of the gland itself are not discussed.
authors.affiliation: Anatomia Patologica, Dipartimento di Anatomia, Patologia Diagnostica, Medicina Legale, Igiene e Sanità Pubblica, Policlinico Universitario, Catania. g.magro@unict.it
authors.forename: G
authors.initials: G
authors.lastname: Magro
authors.forename: A
authors.initials: A
authors.lastname: Torrisi
authors.forename: O
authors.initials: O
authors.lastname: Ippolito
authors.forename: A
authors.initials: A
authors.lastname: Torrisi
authors.forename: M
authors.initials: M
authors.lastname: Bisceglia
mesh_terms: D000273:Adipose Tissue / Q000473:pathology; D000686:Amyloidosis / Q000473:pathology; D044963:Biopsy, Fine-Needle; D002356:Cartilage; D002828:Choristoma / Q000473:pathology; D004848:Epithelium / Q000473:pathology; D006042:Goiter / Q000473:pathology; D006801:Humans; D008210:Lymphocele / Q000473:pathology; D008679:Metaplasia; D009077:Mucins / Q000032:analysis; D018485:Muscle Fibers, Skeletal; D024862:Oxyphil Cells / Q000473:pathology; D010280:Parathyroid Glands / Q000002:abnormalities; D010860:Pigments, Biological / Q000032:analysis; D012469:Salivary Glands; D013950:Thymus Gland; D013955:Thyroglossal Cyst / Q000473:pathology; D013959:Thyroid Diseases / Q000473:pathology* / Q000601:surgery; D013961:Thyroid Gland / Q000737:chemistry / Q000196:embryology / Q000473:pathology* / Q000601:surgery
chemical_list: D009077:Mucins; D010860:Pigments, Biological