Adrenal Abscess
An adrenal abscess is a localized collection of pus within the adrenal gland, most often caused by infection spreading through the bloodstream, superinfection of a prior adrenal hemorrhage, or direct extension from a nearby infection. Adrenal abscesses are uncommon but potentially serious, and prompt diagnosis is important because untreated infection can lead to sepsis, adrenal insufficiency, or rupture. Imaging—particularly CT and MRI—is central to diagnosis, and treatment usually combines antimicrobial therapy with image-guided drainage in appropriate cases and, less commonly, surgery.
What is it?
The adrenal glands are two small triangular organs that sit on top of the kidneys and produce important hormones, including cortisol, aldosterone, adrenaline, and noradrenaline.
An adrenal abscess is a localized collection of infected material within the adrenal gland. It may form when bacteria, fungi, or, less commonly, mycobacteria such as those that cause tuberculosis infect adrenal tissue and the body’s inflammatory response produces a defined collection.
Adrenal abscesses are rare compared with abscesses in other abdominal organs. They are clinically important because they often occur in patients who are already significantly ill and because untreated infection may lead to sepsis, adrenal insufficiency, extension into surrounding tissues, or rupture.
Adrenal abscesses can develop through several mechanisms. Hematogenous spread occurs when an organism reaches the adrenal gland through the bloodstream from another site. This may occur in patients with infective endocarditis, severe systemic infection, injection drug use, urinary or abdominal infection, or another source of bacteremia.
Superinfection of a prior adrenal hemorrhage is another recognized mechanism. A blood collection within the adrenal gland may become secondarily infected, particularly in newborns, immunocompromised patients, and people with serious chronic illness.
Direct extension from an infection involving the kidney, retroperitoneum, spine, or another nearby structure is less common.
Newborns are a particular population in whom adrenal abscess has been reported. Adrenal hemorrhage associated with a difficult birth can become infected and develop into an abscess that may require antimicrobial treatment and drainage.
Risk factors include immunosuppression related to HIV, chemotherapy, transplantation, or immunosuppressive medication; diabetes; injection drug use; infective endocarditis; recent abdominal or urinary infection; prior adrenal hemorrhage; and serious chronic illness.
Tuberculosis, histoplasmosis, cryptococcosis, candidiasis, nocardiosis, and other disseminated infections may involve the adrenal glands, particularly in immunocompromised patients. These infections may produce focal collections, bilateral enlargement, nodules, necrosis, or other imaging abnormalities rather than a typical isolated bacterial abscess.
Reported bacterial causes include staphylococci, streptococci, Gram-negative organisms such as Escherichia coli and Klebsiella species, and anaerobic bacteria. Fungal and mycobacterial organisms are particularly important in immunocompromised patients or those with relevant geographic, exposure, or travel histories.
Symptoms may include fever, chills, flank or upper abdominal pain, fatigue, weight loss, and signs of systemic infection. Symptoms can be nonspecific, and adrenal involvement may be recognized only after imaging is performed for unexplained fever, pain, or sepsis.
Bilateral or extensive adrenal disease may impair hormone production and cause adrenal insufficiency. Symptoms can include severe weakness, dizziness, nausea, vomiting, low blood pressure, low blood sugar, low sodium, and high potassium. Severe adrenal insufficiency can lead to adrenal crisis and shock.
Some chronic infections, including tuberculosis and fungal infections, may produce gradual symptoms over weeks or months rather than an abrupt illness.
Diagnosis combines clinical assessment, laboratory testing, and imaging. Blood tests may show an elevated white blood cell count, although the count may be normal or low in severe infection or immunosuppression. CRP, ESR, and other markers of inflammation may also be elevated.
Blood cultures are important when bloodstream infection or sepsis is suspected, although they may be negative. When drainage or aspiration is performed, material from the abscess is sent for bacterial, fungal, and mycobacterial testing as clinically appropriate to help identify the responsible organism.
Adrenal function may be assessed with cortisol, ACTH, electrolytes, and, when appropriate, additional endocrine testing, particularly when the disease is bilateral or symptoms suggest adrenal insufficiency.
Testing for HIV, tuberculosis, fungal infection, and other infectious causes may be appropriate depending on the patient’s immune status, exposures, geographic history, and clinical presentation.
CT of the abdomen with intravenous contrast is generally the primary imaging test. Findings may include a low-attenuation adrenal collection with peripheral enhancement, surrounding inflammatory change, internal debris, or, in some bacterial infections, gas. These findings are suggestive but are not completely specific because hemorrhage, adrenal pseudocysts, and necrotic tumors may have overlapping appearances.
Ultrasound is frequently used in newborns and can identify complex suprarenal collections. MRI may be helpful when CT findings are uncertain, when further tissue characterization is needed, or when avoiding ionizing radiation or iodinated contrast is important.
Echocardiography may be performed when infective endocarditis is suspected.
Image-guided aspiration or drainage can provide material for microbiologic testing and may also provide source control. Whether it is appropriate depends on the size, location, internal structure, and accessibility of the collection, as well as the patient’s clinical condition.
Because an infected or necrotic adrenal tumor can sometimes resemble an abscess, an underlying lesion may need to be considered. When imaging and clinical findings are indeterminate, pheochromocytoma is particularly important because manipulating this hormone-producing tumor can trigger a dangerous catecholamine release.
Important to Know
An acute adrenal abscess is a potentially serious infection that usually requires prompt evaluation and coordinated treatment, often in a hospital when systemic illness, sepsis, adrenal insufficiency, or the need for drainage is present.
Management is based on the organism, severity of illness, size and structure of the collection, presence of adrenal insufficiency, and underlying source of infection.
Empiric antibiotics covering likely organisms are often started after appropriate cultures have been obtained, provided that obtaining cultures does not delay urgent treatment. The initial regimen depends on the suspected source, severity of illness, immune status, local resistance patterns, and other patient-specific factors.
Once microbiologic results are available, treatment is adjusted to target the identified organism. Suspected or confirmed fungal, mycobacterial, or parasitic infection requires disease-specific therapy, usually in collaboration with an infectious disease specialist.
Image-guided drainage is an important component of treatment for many well-defined bacterial adrenal abscesses, particularly when source control or microbiologic diagnosis is needed. Whether drainage is appropriate depends on the size and structure of the collection, the suspected organism, the patient’s condition, and whether the lesion can be accessed safely.
Percutaneous drainage is commonly performed under CT or ultrasound guidance. Surgery, including open drainage or adrenalectomy, may be needed when percutaneous drainage is not feasible, when the collection is multiloculated or complicated, when infection has ruptured or spread into surrounding tissues, when an underlying tumor is suspected, or when the patient does not improve with less invasive treatment.
Some chronic fungal or mycobacterial adrenal infections may be managed primarily with organism-specific medical treatment rather than drainage, depending on the imaging appearance and clinical circumstances.
Identifying and treating the original source of infection is essential. Infective endocarditis may require prolonged antibiotics and, in selected cases, cardiac surgery. Urinary, abdominal, bloodstream, spinal, and other infections are managed according to their specific source.
Conditions such as diabetes, HIV, medication-related immunosuppression, and other chronic illnesses also require appropriate management. Patients who inject drugs may benefit from addiction treatment and harm-reduction support as part of their overall care.
Adrenal insufficiency requires prompt recognition and treatment. Patients with confirmed or strongly suspected adrenal crisis require urgent glucocorticoid treatment, fluids, correction of electrolyte and glucose abnormalities, and hemodynamic support. Emergency treatment should not be delayed while awaiting confirmatory laboratory results.
Mineralocorticoid replacement may also be required in patients with primary adrenal insufficiency. Adrenal function may recover after successful treatment in some patients, while others may need long-term hormone replacement.
Patients requiring ongoing hormone replacement receive education about stress dosing during illness, injury, or surgery; medical alert identification; and emergency glucocorticoid injection kits.
When the diagnosis is uncertain and an underlying adrenal tumor remains possible, pheochromocytoma should be considered before biopsy, aspiration, or surgery because manipulating one can trigger a dangerous catecholamine surge. In urgent cases, the risks and timing of hormonal testing and source control are determined by the treating multidisciplinary team.
Supportive care may include pain management, intravenous fluids, nutritional support, treatment of sepsis, monitoring of vital signs and laboratory results, and prevention of complications.
Follow-up imaging may be used to document improvement or resolution and to determine whether an underlying adrenal lesion becomes visible after the infection or hemorrhage subsides.
Care may involve hospitalists, infectious disease specialists, endocrinologists, interventional radiologists, surgeons, cardiologists when endocarditis is present, and primary care clinicians.
Patient education includes completing the prescribed antimicrobial course, attending follow-up appointments, recognizing warning signs, and following adrenal-insufficiency precautions when applicable.
Red-flag symptoms include sudden severe abdominal, flank, or back pain; fainting; rapid heart rate; cool or clammy skin; signs of shock; high fever with shaking chills; severe shortness of breath; confusion; severe weakness; low blood sugar; or rapid clinical deterioration.
These symptoms require immediate emergency evaluation because they may indicate adrenal crisis, severe sepsis, rupture, uncontrolled bleeding, or another serious complication.