In this case report, we showed a subject who had non-tuberculous mycobacterial infection and Addison’s disease triggered by the infection. It is known that MAC pulmonary disease accounts for a majority of lung non-tuberculous mycobacterial infection. In this subject, however, pathogen bacteria were mycobacterium abscessus (Mab), but not MAC. It is noted here that Mab is very rare as a cause of Addison’s disease. Addison’s disease is primary adrenal failure in which cortisol secretion from the adrenal gland is markedly reduced. In this subject, it is likely that the development of calcification was closely associated with destruction of the adrenal gland. Although the consolidation in the left lung was drastically reduced in this subject, endogenous adrenal function was not recovered even after steroid therapy. Therefore, we continued hydrocortisone therapy. It seems that once calcification is developed to some extent, it is difficult to restore adrenal function. We assume that if we had found Addison’s disease at an earlier stage before the development of calcification in the adrenal gland, we might have, at least in part, restored adrenal function to some extent in this subject.
Infection, especially tuberculous infection, is one of main causes of Addison’s disease. In typical Addison’s disease due to adrenal gland tuberculous, swelling of both adrenal glands together with calcification is observed in some imaging examination. Therefore, we suspected this subject of having adrenal tuberculosis, but she had no past or family history of tuberculosis and QuantiFERON test was negative. In PCR test using bronchial lung lavage fluid, mycobacterium tuberculosis complex was negative. These findings ruled out the possibility of adrenal tuberculosis. It is known that MAC pulmonary disease accounts for the majority of non-tuberculous mycobacterial infection. Therefore, we suspected her of having MAC pulmonary disease, but anti-MAC antibody was negative. It is also known that mycobacterium avium and mycobacterium intracellulare are main pathogen bacteria of MAC pulmonary disease. In this subject, however, both bacteria were negative in PCR test using bronchial lung lavage fluid. These findings ruled out the possibility that this subject had MAC pulmonary disease. Mycobacterium abscessus (Mab) was positive in bronchial lung lavage fluid culture. We finally diagnosed this subject with Addison’s disease triggered by infection with Mab, but not by tuberculous mycobacterial infection or MAC pulmonary disease. If adrenal gland biopsy had been performed, the biopsy data would have strengthened the above-mentioned diagnosis. However, we did not perform the biopsy in consideration of her age (83 years old), possible risk of infection and the hope of this subject that she did not want us to perform such biopsy.
The incidence of Mab pulmonary disease is slightly increasing, but it is still very rare [6,7,8,9,10]. Indeed, it was reported that Mab infection accounted for only 3% in non-tuberculous mycobacteriosis . Mab infection is more often observed in female compared to male, although its reason remains unknown. Mab infection is usually treated with various kind of antibiotics, and it is often difficult to appropriately control the infection especially in subjects with serious underlying disease who are compromised host [11,12,13]. In serious cases, surgical operation is needed to treat Mab pulmonary disease. MAC infection is often found as an underlying disease of Mab pulmonary disease. In this subject, after starting hydrocortisone therapy, sodium level was increased and eosinophil number was decreased and her symptoms were markedly mitigated. Finally, she was discharged. Mycobacterium abscessus was detected in bronchial lung lavage fluid culture 20 days after discharge. She had no subjective symptoms at that time. Mab infection is usually treated with antibiotics. It has been reported, however, that Mab pulmonary disease is not aggravated even without any treatment in some subjects without serious underlying disease [11,12,13]. Therefore, we did not start any therapy with antibiotics in this subject. Fludrocortisone is sometimes used in subjects with Addison’s disease, but since salt intake in Japanese is higher compared to other countries, hydrocortisone, but not fludrocortisone, is used as a first-line drug in Japan. Therefore, we used hydrocortisone. However, Mab pulmonary disease in this subject was mitigated without any specific treatment. Since Mab pulmonary disease is sub-classified into three subtypes (M. abscessus subsp. abscessus，M. abscessus subsp. massiliense，M. abscessus subsp. Bolletii) based on gene sequence analysis , we assume that the prognosis, at least in part, depends on such subtype of bacteria. It has been also reported that the prognosis depends on host immune response in each subject. For example, when subjects have diabetes mellitus with poor glycemic control, the prognosis of Mab pulmonary disease would be poor. This subject had type 2 diabetes mellitus but glycemic control was good (HbA1c, 6.2%). We assume that good glycemic control was associated with the recovery from Mab pulmonary disease without any specific treatment. As described above, MAC infection is often found as an underlying disease of Mab pulmonary disease, and it is known that bacteria can change from MAC to Mab. In this subject, however, since anti-MAC antibody was negative. We think that this ruled out the possibility that this subject suffered from MAC infection.
There is a limitation in this case report. Autoimmune origin of adrenal insufficiency is the most common cause for adrenal failure in developed countries. In the present case, autoimmunity was excluded based upon CT adrenal image. We failed to examine serum level of adrenal autoantibody. We should have examined adrenal antibody in this subject in order to completely exclude the possibility of autoimmunity.
Taken together, we should bear in mind the possibility of Addison’s disease triggered by non-tuberculous mycobacterial infection. We should check other pathogen bacteria carefully even when we exclude the possibility of adrenal tuberculous and MAC pulmonary disease.