A Pseudotumoral Goiter Revealing the Fibrous Variant of Hashimoto’s Thyroiditis: A Case With Multidisciplinary Diagnostic Challenges

The fibrosing (or fibrous) variant of Hashimoto's thyroiditis is an uncommon entity that may closely mimic a malignant thyroid tumor due to its clinical presentation and morphological features. We report the case of a patient with progressively worsening compressive goiter in the setting of established hypothyroidism, in whom imaging findings suggested a pseudotumoral lesion. Histopathological examination of the thyroidectomy specimen demonstrated diffuse thyroid fibrosis associated with a dense lymphoplasmacytic infiltrate forming lymphoid follicles, along with oncocytic and squamous metaplasia, without evidence of malignancy. This case highlights the pivotal role of thorough histopathological assessment in establishing the correct diagnosis of this rare condition and in excluding neoplastic processes, thereby preventing unnecessary aggressive management.