Of those 16,925 patients, 2,903 were also diagnosed with a concomitant malignancy during that time period. Compared with patients with no itching diagnosis during that time period, the pruritus patients more likely to have a concomitant malignancy, with an OR of 5.76 (95% confidence interval, 5.53-6.00), Dr. Kwatra and his colleagues found.
Malignancies most strongly associated with pruritus included those of the skin, liver, gallbladder and biliary tract, and hematopoietic system.
Among hematologic malignancies, pruritus was most strongly linked to myeloid leukemia and primary cutaneous lymphoma, while among skin cancers, squamous cell carcinoma was most strongly linked.
Whites had higher odds of any malignancy versus blacks, according to investigators, with ORs of 6.12 (95% CI, 5.81-6.46) and 5.61 (95% CI, 5.21-6.04), respectively.
Blacks with pruritus had higher ORs for hematologic and soft tissue malignancies including those of the muscle, fat, and peripheral nerve, investigators said, while whites had higher ORs for skin and liver malignancies.
The investigators also looked at the prevalence of skin eruptions in patients with pruritus and malignancy. “Eruption is variable by malignancy type and points to differing underlying mechanisms of pruritus,” they reported.
The highest rates of skin eruption were in patients with myeloid leukemia at 66%, followed by bone cancers at 58%, lymphocytic leukemia at 57%, multiple myeloma at 53%, and bronchus at 53%. The lowest rates of skin eruption were in patients with gallbladder and biliary tract, colon, pancreas, and liver malignancies.
Dr. Kwatra reported that he is an advisory board member for Menlo Therapeutics and Trevi Therapeutics.
SOURCE: Kwatra SG et al. J Am Acad Dermatol. 2018 Sep 11. doi: 10.1016/j.jaad.2018.08.044.