Tests
1st tests to order
clinical diagnosis
Test
Diagnosis is typically clinical; tissue biopsy is rarely needed.[32]
If diabetes is suspected by a strong family history or symptoms, the patient presents with generalized GA, or the patient is 40 years or older, a fasting blood sugar test is recommended. A weak association has been described.[11]
Result
typically determined by physical exam findings
Tests to consider
skin biopsy
Test
Rarely needed, but an incisional biopsy can be helpful if a differential diagnosis such as subcutaneous sarcoidosis or lymphoma seems more likely.
Result
palisading or interstitial granular pattern confined to superficial and mid dermis; focal degeneration of collagen and elastin fibers; mucin characteristic with a perivascular interstitial lymphocytic infiltrate
fasting blood sugar
Test
If diabetes is suspected by a strong family history or symptoms, the patient presents with generalized GA, or the patient is 40 years or older, a fasting blood sugar test is recommended. A weak association has been described.[11] Fasting blood sugar is rarely useful for children.
Result
fasting blood glucose ≥126 mg/dL (≥7 mmol/L) is a criterion for diagnosis of diabetes
thyroid function tests
lipid screening
Test
Hyperlipidemia may be associated with GA, including abnormalities in total cholesterol, triglycerides, and low-density lipoprotein cholesterol levels.[14]
Result
may be abnormalities in total cholesterol, triglycerides, and low-density lipoprotein cholesterol levels
hepatitis screen
Test
Cases of GA developing in patients with hepatitis B (HBV) and hepatitis C (HCV) have been reported.[28][29]
If HBV or HCV is suspected, consider testing for HBV surface antigen, IgM anti-HBc, IgG anti-HCV, and PCR for HCV RNA to screen for concomitant HBV or HCV infection.
Serologic evidence of HBV or HCV may weakly support diagnosis of GA but no diagnostic value is attached to negative results.
If patients have serologic evidence of HBV or HCV, further workup (e.g., serum liver aminotransferase levels) and referral to infectious disease specialists may be indicated.
Result
positive in patients with associated hepatitis B or C infection
HIV testing
Test
There is an association described between HIV and GA (termed HIV-associated GA). This may be generalized or localized to atypical sites such as the penis.[27]
If HIV infection is suspected, appropriate counseling and testing should be considered. Serum HIV ELISA or rapid testing should be ordered when HIV testing is indicated. False negatives may occur during the window period immediately after infection before antibodies to HIV have occurred. A positive result should be confirmed with a Western blot or second ELISA.
If patients have serologic evidence of HIV, referral to infectious disease specialists is indicated.
Result
positive in patients with associated HIV infection
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