Clinical and Biochemical Correlates of Pyramidal Lobe Variations: An Observational Study on Thyroid Function And Pathological Outcomes

Abstract

The human thyroid gland features significant anatomical variability, notably the persistence of the pyramidal lobe and thyroglossal remnants originating from embryonic descent. While traditionally viewed as incidental, the functional and pathological relevance of these structures in endocrine disorders and thyroid surgery remains underexplored. This observational cross-sectional study evaluated 210 subjects (combining 145 clinical surgical patients and 65 cadaveric dissections) using high-resolution cervical ultrasonography, intraoperative assessment, multiplex biochemical assays (TSH, FT4, FT3, anti-TPO, thyroglobulin [Tg], and serum liver enzymes including Alanine Aminotransferase [ALT], Aspartate Aminotransferase [AST], and Alkaline Phosphatase [ALP]), and histopathological evaluations. A pyramidal lobe was identified in 43.8% of cases (n = 92), with the majority originating from the thyroid isthmus (52.2%) or the left lobe (29.3%). Pyramidal lobe hypertrophy was significantly associated with elevated serum TSH (4.82 ±2.15 vs. 2.14 ± 1.08 µIU/mL, p < 0.001), higher serum thyroglobulin levels (64.2 ±28.7 vs. 22.5 ±11.4 ng/mL, p < 0.001), an increased frequency of anti-TPO positivity (67.4% vs. 30.4%, p < 0.001), and subtle variations in serum liver enzymes reflecting systemic metabolic adaptations. Strong positive correlations were confirmed between pyramidal volume and serum Tg levels (r = 0.68, p < 0.001). Furthermore, histological evaluations revealed extensive pyramidal involvement in Graves' disease, Hashimoto's thyroiditis, and papillary thyroid carcinoma. Pyramidal lobe variations and hypertrophy are highly prevalent and directly correlate with altered thyroid function, autoimmune activity, elevated thyroglobulin levels, and hepatic enzyme dynamics. Recognizing these structures is crucial for radiologists, endocrinologists, and surgeons to optimize diagnostic evaluations, prevent incomplete surgical resections, and ensure reliable postoperative surveillance.