Diffuse thymic fibrosis: histologic pattern of injury or distinct entity?
Thymic fibrosis in the absence of another primary thymic lesion, such as a neoplasm or cyst, is unusual. We identified 6 cases of primary extensive thymic fibrosis that developed in 3 men and 3 women, aged 28 to 60 years, mean 48 years. Patients had limited or no symptoms. Two patients had dyspnea and 1 had cough and hemoptysis. One female patient had myasthenia gravis. The lesions measured 3.5 to 17 cm in greatest dimension, mean 8 cm, and were confined to the anterior mediastinum as determined by imaging, intraoperative notes, and/or gross examination. All cases showed diffuse fibrosis with variable collagen deposition, lymphoplasmacytic infiltrates, and involution/atrophy of thymus. One case had rare IgG4-positive plasma cells and focal obliterative phlebitis. The histology showed overlap with that of IgG4-related sclerosing disease, which to our knowledge has not been documented earlier in this location. Although the etiology of the lesions is undetermined, altered immunity and/or infection may play a role.
Shilo
Konstantin
K
Department of Pulmonary and Mediastinal Pathology, Armed Forces Institute of Pathology, Washington, DC 20306, USA. shilokna@hotmail.com
Mani
Haresh
H
Deshpande
Charu
C
Ozbudak
Irem H
IH
Travis
William D
WD
Galvin
Jeffrey R
JR
Franks
Teri J
TJ
D000328:Adult; D003094:Collagen / Q000378:metabolism; D005260:Female; D005355:Fibrosis; D006801:Humans; D008206:Lymphatic Diseases / Q000209:etiology / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D013950:Thymus Gland / Q000293:injuries* / Q000378:metabolism / Q000473:pathology*
D003094:Collagen