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

## TL;DR

A rare case of fibrous Hashimoto’s thyroiditis was mistaken for a thyroid tumor, highlighting the need for detailed histopathological analysis to avoid misdiagnosis.

## Contribution

This case report presents a rare fibrous variant of Hashimoto’s thyroiditis with pseudotumoral features, emphasizing diagnostic challenges and the importance of histopathology.

## Key findings

- The patient presented with a compressive goiter and hypothyroidism, mimicking a thyroid tumor.
- Histopathology revealed fibrosis and lymphoid infiltration without malignancy, confirming the fibrous variant of Hashimoto’s thyroiditis.
- The case underscores the necessity of histopathological evaluation to prevent unnecessary aggressive treatment.

## Abstract

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.