pˈɪɾɪŋ ˈɔːlsoʊ mˈeɪ biː kˈɔːzd baɪ ɐ vɚɹˈaɪəɾi ʌv sɪstˈɛmɪk dɪzˈiːzᵻz, ɪŋklˈuːdɪŋ ɹɪˈæktɪv ɑːɹθɹˈaɪɾɪs ænd ˈʌðɚ kənˈɛktɪv tˈɪʃuː dɪsˈoːɹdɚz, sˌɑːɹkɔɪdˈoʊsɪs, pˈɛmfɪɡəs, ɐloʊpˈiːʃə ˈɛɹiəɾə, ænd ɪŋkˌɑːntɪnˈɛnʃə pɪɡmˈɛnti.
Pitting also may be caused by a variety of systemic diseases, including reactive arthritis and other connective tissue disorders, sarcoidosis, pemphigus, alopecia areata, and incontinentia pigmenti.