| Autoimmune/inflammatory disorders |
| Metabolic syndrome |
| Crohn disease |
| Ulcerative colitis |
| SAPHO syndrome |
| Pyoderma gangrenosum |
| Behçet's disease |
| Spondylarthropathy |
| Acne conglobata alone or in the setting of the follicular occlusion triad* |
| Psoriasis |
| PAPASH syndrome |
| PASH syndrome |
| Malignancy |
| Squamous cell carcinoma |
| Adenocarcinoma |
| Genetic disorders |
| Pachyonychia congenita |
| Dowling-Degos disease |
| KID syndrome |
| Down syndrome |
| Other |
| Anemia |
| Myocardial infarction |
| Cerebrovascular accident |
