High Cortisol Levels May Impair Immune System, Spark Infection

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by Patricia Inacio PhD |

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A generalized skin infection due to Mycobacterium chelonae — a rapidly growing type of bacteria — may be a manifestation of an impaired immune system due to Cushing’s disease linked to high cortisol hormone levels caused by an ACTH-producing tumor, a case report shows.

The case highlights the need for extensive tests whenever a patient experiences a generalized infection but no immediate cause for a potentially impaired immune system, the researchers said.

The study, “Disseminated cutaneous Mycobacterium chelonae infection as a presenting sign of ectopic adrenocorticotropic hormone syndrome,” was published in the journal JAAD Case Reports.

Cushing’s syndrome is a condition characterized by too much cortisol — called hypercortisolemia — in the body’s circulation. In many cases, it is caused by a tumor in the pituitary gland, which produces greater amounts of the cortisol-controlling adrenocorticotropic hormone, known as ACTH.

Ectopic Cushing’s syndrome arises when the overproduction of ACTH is induced by a malignant tumor outside the pituitary gland — most commonly, a small cell lung cancer.

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This case report describes a 43-year-old man treated after a three-week history of tender red nodules (called erythematous nodules) due to inflammation on his left upper arm and right leg, as well as swelling (edema) in both legs. The nodules were growing in a sporotrichoid pattern, which means they were spreading along the lymph nodes in the body.

One week of treatment with the broad-spectrum antibiotic doxycycline did not lead to any observable improvements. The patient did not have a fever, chills, nausea, vomiting, or diarrhea.

His medical history included a recent diagnosis of high blood pressure (hypertension) and a skin infection triggered by the Serratia marcescens bacteria and shingles.

In the seven months prior to his clinical visit, he had gained 50 pounds and developed swelling of the lower legs. He also experienced a decreased libido and depression.

Physical examination revealed obesity, fat accumulation along the spine, a rounded face, stretch marks on the abdomen and armpits, and muscle weakness.

A biopsy conducted on one of his nodules confirmed the presence of a granuloma, or small area of inflammation, and recurring inflammation in the subcutaneous or deepest layer of skin fat (suppurative panniculitis).

These granulomas tested positive for a rapidly growing mycobacterium, or a non-tuberculosis type of bacteria, called Mycobacterium chelonae. This bacterium most commonly causes infection of the skin and in soft tissues. The patient then received appropriate antibiotic treatment.

In the meantime, blood and urine tests revealed elevated levels of cortisol — 46.5 micrograms per deciliter, mcg/dL (blood: normal range 4.5-22.7 mcg/dL), and 660 mcg/24 hours (urine: normal range 3.5-45 mcg/24 hour). Cortisol is a steroid hormone that regulates a wide range of important body functions, impacting metabolism and immune responses.

MRI scans showed no abnormalities in the pituitary glands. However, an ACTH-secreting carcinoid tumor — a type of slow-growing cancer — was identified in the left lung, specifically in a tongue-shaped region called lingula.

Given his elevated cortisol levels, the patient was hospitalized and received treatment with ketoconazole (sold as Nizoral among other brand names), a medication that works to lower cortisol levels.

He then underwent surgery to remove the tumor. In the first day after surgery, his cortisol levels dropped to 1.4 mcg/dL, “suggestive of surgical cure,” the researchers wrote.

The patient was given hydrocortisone, a cortisol-like steroid medication, after surgery, with a plan for tapering it down once cortisol reached normal levels. Also, two antibiotics were continued for the treatment of the M. chelonae infection.

One month following surgery, the man’s levels of cortisol had decreased dramatically and his skin nodules were nearly completely resolved.

“To our knowledge, a single case report previously described disseminated M. chelonae in a patient with endogenous hypercortisolemia (Cushing syndrome),” the researchers wrote. “Here, we describe a case, in which endogenous hypercortisolemia secondary to ectopic adrenocorticotropic hormone (ACTH) syndrome resulted in disseminated M. chelonae infection.”

Previous evidence has shown that elevated cortisol levels can suppress the immune system, and increase the risk of opportunistic infections.

According to the team, “patients with disseminated NTM [non-tuberculosis mycobacterium], without a known cause for immunosuppression, should have an expedited work-up for potential underlying etiologies [causes] to prevent further complications,” they wrote.