What is the etiology of bilateral avascular necrosis (AVN) in a patient with sebosporiasis, treated with topical fluocinolone acetonide (fluocinolone acetonide) and a history of bilateral core decompression with bone marrow aspirate injection?

Diagnostic Workup for Bilateral Avascular Necrosis Etiology

In a patient with bilateral AVN and sebopsoriasis treated with topical fluocinolone acetonide, you must systematically evaluate for corticosteroid exposure (including systemic absorption from topical therapy), alcohol use, hyperlipidemia, hypercoagulable states, HIV infection, and hemoglobinopathies, as these represent the most common identifiable causes of bilateral AVN. 1, 2

Primary Etiologic Considerations

Corticosteroid Assessment

• Quantify total corticosteroid burden including any systemic therapy, as high-dose glucocorticoids increase AVN risk at least 1.5-fold compared to low-dose regimens 1
• Evaluate for systemic absorption from topical fluocinolone acetonide, particularly if applied to large body surface areas or under occlusion, though this is an uncommon cause 3
• Document duration and dosing of any oral, intravenous, or intramuscular corticosteroids, as AVN typically becomes detectable 1-6 months after exposure to high-dose therapy 4

Metabolic and Hematologic Workup

• Obtain fasting lipid panel to screen for hyperlipidemia, which is a well-established risk factor for AVN 1, 2, 5
• Screen for hypercoagulable states including antiphospholipid antibodies, protein C/S deficiency, Factor V Leiden, and prothrombin gene mutation 1, 2
• Test for hemoglobinopathies, particularly sickle cell disease or trait, as these significantly increase AVN risk 2

Infectious and Toxic Exposures

• HIV testing is mandatory, as HIV infection itself increases AVN risk independent of antiretroviral therapy 1, 2
• Quantify alcohol consumption using standardized screening tools, as alcohol abuse is a major independent risk factor 2

Additional Diagnostic Considerations

Renal and Transplant History

• Evaluate for history of dialysis or organ transplantation, as longer duration of dialysis prior to transplantation increases AVN risk 3, 1
• In transplant patients, review immunosuppression regimens, as cyclosporine may reduce AVN incidence by permitting lower steroid doses 3

Recent Viral Illness

• Screen for recent COVID-19 infection, as the combination of COVID-19 and corticosteroid therapy substantially increases AVN risk through both hypercoagulability and steroid effects 6, 7

Imaging to Assess Disease Extent

Contralateral Hip Evaluation

• MRI of the contralateral hip is essential, as 70-80% of nontraumatic AVN cases are bilateral, and early detection allows for joint-preserving interventions 8
• MRI can detect asymptomatic AVN in approximately 5% of at-risk patients before radiographic changes appear 1, 2

Quantification of Necrotic Volume

• Determine necrotic volume percentage on MRI, as femoral heads with ≥30% necrotic volume progress to collapse in 46-83% of cases, while those with <30% progress in <5% of cases 2, 8
• This measurement directly impacts treatment decisions, as joint-preserving interventions are only effective before subchondral collapse 2

Critical Pitfalls to Avoid

• Do not overlook systemic causes even when topical corticosteroid use is documented, as topical absorption alone rarely causes AVN 3
• Do not delay workup waiting for symptoms to worsen, as early detection before articular collapse is critical for joint-preserving options 2, 8
• Do not assume unilateral disease without bilateral imaging, given the high rate of bilateral involvement in nontraumatic AVN 8
• Do not attribute AVN solely to age or osteoarthritis without completing the full etiologic workup, as identifying modifiable risk factors (alcohol, hyperlipidemia, hypercoagulability) can prevent progression in the contralateral hip 1, 2