What is that nodule? A diagnostic approach to evaluating subcutaneous and cutaneous nodules.

The evaluation of patients with subcutaneous nodules remains a diagnostic challenge. The presence of nodules can be a clue to an underlying systemic disease; however, the varied presentations of nodules and numerous disease associations make the assessment of patients with nodules far from simple. With further investigation into the appearance, location, and symptoms associated with nodules, the clinical significance of these lesions can become clearer and aid in logical diagnostic evaluation. We have reviewed the causes of nodules with emphasis on those associated with rheumatic disease and provide guidelines for nodule evaluation to better characterize disease association and lead to directed diagnostic assessment.