“…However, when detecting thymus hyperplasia, it is necessary to remember about the possibility of a secondary process against the background of various diseases, as well as neoplasms [10,14]. According to some studies, persons with thymic-lymphatic dysgenesis are characterized by biological instability, as a result of which sudden death may occur from the effects of some, even minor, factors [25]. The presented case allowed the authors to prepare the basis for increased attention to the thymus in subsequent cases of sudden death.…”