Thymic Epidermoid Cyst: Clinical and Imaging Manifestations of This Rare Anterior Mediastinal Mass

Abstract

Thymic epidermoid cysts are an extremely rare entity. These arise from epidermal cells that migrate to the thymus. The radiologic diagnosis of this rare lesion is challenging. We describe a case of an otherwise healthy 35-year-old woman who presented with an acute onset of chest pain and shortness of breath. She was found to have an anterior mediastinal mass. The imaging findings were, however, not characteristic for any single diagnostic entity. Since the imaging was inconclusive, surgical resection was performed for definitive diagnosis. The mass was found to be a thymic epidermoid cyst. This case underlines the significance for radiologists to be aware that epidermoid cysts can occur in the thymus and should be considered in the differential diagnosis for a heterogeneous anterior mediastinal mass.

A rare case of intrathymic epidermoid cyst

“…Thus, the epidermoid cyst is characterized by a heterogeneous structure on CT, lack of FDG accumulation, heterogeneous structure on MRI and diffusion restriction in DWI mode. 11 The differential diagnosis is initially based on the localization of the mass of a chest X-ray or CT (Fig. 6).…”

“…Despite this, epidermoid cysts of the thymus are an extremely rare histological variant and are described only in a few cases in the literature, which is why it is rarely included in the differential diagnosis. [11][12][13][14] Since it is often difficult to make a conclusion based on imagistic examination the patients are operated in order to obtain a histology result and reliably exclude an oncological process.…”

Thymic Dermoid Cyst: A Rare Anterior Mediastinal Mass

“…Rare cases of thymic dermoid cysts have been reported, and thymus is an unusual location to form and contain these masses (12). Sequestration and proliferation of epidermal cells originating from ectoderm within the thymic tissue might be the main reason for the formation of these cysts in the thymus (8,12,13). It can be a rare differential diagnosis of anterior mediastinal masses such as neoplasm of thymus origin, thymoma, lymphoma and teratoma (12).…”

“…Thymic dermoid cysts are extremely rare, the location in the thymus gland is atypical and imaging findings are nonspecific. They usually have a good prognosis, but to obtain tissue diagnosis and exclude other entities, surgical resection is required (12).…”

Mediastinal Epidermoid Cyst in a 5-Year-Old Girl

“…Mediastinal epidermoid cysts in children are very rare with only four cases reported individually, 5 6 7 8 and another two within a larger case series. 9 Cases have been reported in various locations of the mediastinum including the thymus 10 and outwith the mediastinum like the gastrointestinal tract or spine. 11 12 All the patients with available demographics were adults.…”