First report of hemorrhage into the thyroid gland is described by Simon in 1894. To date reported cases about haemorrhage into thyroid was caused by trauma, cervical hyperflexion, a manual blow to the back of the head, lifting a heavy weight, straining at defecation, and even during household work . And to date eggshell calcification in thyroid gland was reported but none of them was caused after intrathyroidal hemorrhage as in our case report.
This case is unusual in that eggshell calcification of intrathyroidal hemorrhage was located in the retrosternal, a finding not previously reported in the English literature. Ring-shaped calcifications may simulate the eggshell appearance. These include aneurysms of the great vessels, parathyroid tumors, pulmonary arteries in pulmonary arterial hypertension, thymic cysts, and thyroid tumors . We had performed angio-CT for communications of vessel with the mass. Angio-CT was reported as no communications occured with the mass.
Bleeding is the most frequent complication of oral acetylsalicylic acid therapy. The most common locations for bleeding include gastrointestinal and genitourinary tracts. Platelet inhibition via acetylsalicylic acid can increase the risk of bleeding but it is used safely in cardiovascular diseases and stroke . Our patient had no underlying coagulopathy except that he had acetylsalicylic acid usage for two years the gastrointestinal bleeding episode. It is possible, although unlikely, that a mild coagulopathy from aspirin ingestion predisposed him to this event. But in our case, we could not predict that acetylsalicylic acid usage was the main casuse of intrathyroidal bleeding.
Eggshell calcification of thyroid is rare and only three cases have been reported. One was an ultrasonic appearance of an eggshell calcification of a thyroid nodule reported in 1978 by Gooding GA , other was eggshell calcification in follicular thyroid carcinoma reported in 2005 by Cheng SP and et al . The last and recent one was double eggshell calcification in thyroid in 2007 by Vandemergel X .
Egg-shell calcification is one of the patterns of dystrophic calcifications and is often associated with multinodular goiters . It was generally thought to be an indicator of benignancy , however, cases of papillary carcinoma  and undifferentiated carcinoma  associated with this type of calcification have been reported. In Taki S et al series, 43% (6/14) of this type of calcification was associated with cancer, and all of them were papillary carcinoma .
Typical benign nodules are well defined, mostly cystic, and hyperechoic relative to adjacent parenchyma (96% benign). These nodules have eggshell calcification and a thin, echolucent halo around the entire lesion, and they always contain internal debris. Lesions demonstrating eggshell calcification and a thin echolucent halo around the entire lesion are most often benign. Some authors have found that the halo sign is present in 21–33% of thyroid cancers. But Cheng SP considered that type of thyroid calcification is not a good indicator of benignancy .