In familial cases, an autosomal dominant mode of transmission has been proposed. The presence of systemic disease appears to be common in black South African and Japanese patients, but is much less likely among Caucasian patients. Osteitis Chronic diarrhea Scleroderma Resolution of PR has been noted with treatment of the underlying malignancy. One Japanese patient with PR had multiple myeloma, while another had myeloma and hepatic cirrhosis. The association with systemic disease appears much less common among Caucasian patients.
Some cases are familial, however, suggesting an autosomal dominant pattern of inheritance.
In one Sardinian family, PR occurred in 3 siblings, whose father had typical ichthyosis vulgaris. Such an association likely is coincidental, because favism is common among individuals from that family s place of origin. The fourth had mild hypertension. Examination with Wood s light will be useful in cases suspicious for extraflexural erythrasma. Use history and physical findings directed toward any underlying systemic diseases to guide further laboratory and imaging studies.