Laboratory Studies
Laboratory studies may be helpful if the diagnosis of granuloma annulare cannot be ruled out with a complete history emphasizing issues such as diet, weight loss, and/or fever. If an accurate history is unobtainable, a CBC count and erythrocyte sedimentation rate (ESR) should be obtained.
No laboratory studies are needed to make the diagnosis of pyogenic granuloma. CBC count, human chorionic gonadotropin (HCG), HIV, and biochemical profiles are needed only if there is concern for other etiologies.
Check blood glucose level if there is concern of diabetes mellitus and granuloma annulare.
Check rheumatoid factor if symptoms of rheumatoid arthritis are present.
Imaging Studies
Granuloma annulare
Radiographs are not necessary for diagnosis of granuloma annulare but may be helpful if other problems are suspected.
In granuloma annulare, the lesion is soft tissue mass without any calcification or bony involvement.
Pyogenic granuloma
Imaging studies are not useful in pyogenic granuloma.
Procedures
Skin biopsy
To obtain a specimen, a 22- or 24-gauge needle may be gently passed tangentially just below the superficial capsular layer of the lesion, then flushed with saline to yield a small but adequate specimen.
Skin biopsy is diagnostic for granuloma annulare. Because the lesions regress, biopsy is needed only when a definitive diagnosis is required.
Skin biopsy is also diagnostic for pyogenic granuloma.
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Granuloma annulare. Courtesy of Wikimedia Commons (Mierlo at English Wikipedia).
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Pyogenic granulomas are usually solitary lesions. The fingers and hands are common locations for these to develop. A history of minor trauma at the site shortly before development of the lesion is frequent.
