Multidetector computed tomography evaluation of normal thymus and variations with age.

Background: Thymus is a T-cell-producing lymphoid organ that appears prominent in the paediatric population and involutes in size with ageing. The gland shows a wide variety of appearances across different age groups. The purpose of the study is to evaluate the computed tomography (CT) appearance of thymus gland in the normal population with a focus on size, CT attenuation and fatty infiltration in different age groups. Patients and Methods: This is a retrospective study done after taking approval from the Institutional Ethics Committee. Patients undergone CT scans of the thorax were identified from our database. All evaluations were done in non-contrast CT scans. Patients having underlying diseases that may have associated thymic abnormality were excluded. The appearance of thymus and the presence of fatty replacement were assessed. The size of thymus (length and thickness of right limb and left limb) and non-contrast CT Hounsfield unit (HU) value of thymic tissue were measured and compared in various age groups. Results: Four hundred and fifty patients were included, 262 (58.2%) were male. Mean age was 33.6 ± 17.1 years, range (3 months-80 years). The size of thymus was observed to decrease with increasing age. The mean age of complete fatty replacement in our study was 45 years. Complete fatty replacement was noted in all cases with an age of more than 60 years. The most common shape was arrowhead, and the most common location was pre-aortic and para-aortic location. Non-contrast CT HU value was maximum in infants and gradually decreased with advancing age. Conclusion: Even normal thymus can show varied appearance on CT which changes with the age of the patient being imaged. A comparison with normative data could help differentiate normal from abnormal glands to avoid unnecessary intervention.

Recurrent giant simple hepatic cyst: an unusual cause of dyspnoea in an elderly man.

An 88-year-old man presented to the emergency department with exertional dyspnoea and orthopnoea. Clinical examination revealed mildly raised jugular venous pressure, increased respiratory rate, palpable non-tender hepatomegaly and reduced right basal breath sounds. Ultrasonography showed a large right simple hepatic cyst, multiple small left hepatic and renal cysts. A non-contrast CT scan revealed a large, right hepatic thin-walled cyst of volume 4.2 L, exhibiting few thin septae and tiny nodular mural calcifications. Pressure effects were elevated right haemidiaphragm, right atrial compression and adjacent atelectasis. He had a similar episode 2 years ago, treated by percutaneous needle aspiration. Giant simple hepatic cysts are rare and present when symptomatic due to pain, mass effect on adjacent organs, infection or rupture. These may unusually cause dyspnoea or orthopnoea by compressing cardiac chambers. Simple aspiration has a high recurrence rate. Percutaneous sclerosant injection, laparoscopic deroofing and cystectomy are better treatment modalities.