A team of researchers set out to assess the risk of hematologic cancer in patients with undifferentiated pruritus and developed a retrospective cohort study to analyze medical records of 327,502 patients and 327,502 control subjects. Their findings were published in JAMA Dermatology.

The researchers assessed the risks for developing Hodgkin lymphoma, non-Hodgkin lymphoma, lymphocytic leukemia, myeloid leukemia, myelodysplastic syndrome, multiple myeloma, Waldenström macroglobulinemia, monoclonal gammopathy, and polycythemia vera.

The first year after diagnosis was determined to be critical. The highest risk of hematologic cancer was within 12 months of initial diagnosis for the patients with pruritis. After that, the risks were “still significantly higher but more comparable with that of control patients,” according to the researchers.

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When looking at specific cancers, the researchers indicated that in patients with pruritus the highest absolute risk of a non-Hodgkin lymphoma diagnosis in 1 year (0.117% vs 0.050%; P <.001) and 5 years (0.222% vs 0.134%; P <.001). The highest absolute risk for monoclonal gammopathy was 5 years (0.196% vs 0.145%; P <.001) and 10 years (0.235% vs 0.176%; P <.001).

Ultimately, the authors concluded, clinicians should conduct a “thorough review of symptoms and assessment of cancer risk factors” when they are determining what course of treatment to recommend for patients with undifferentiated pruritus. This careful consideration is especially important during the first year after the presentation of pruritus.

The researchers also looked at serum LDH levels and found that while the patients with pruritus did have higher serum LDH levels, those levels did not seem to be associated with a higher risk of cancer.

The study was limited by the use of ICD-10 codes for the patients’ diagnoses, as those could have been liable to misclassification and could also affect the timing of the development of the cancer. The researchers also pointed out that “despite the identified elevated [relative risks] of cancer, absolute risk differences are low, and most patients with undifferentiated pruritus will not have an underlying hematological cancer.”

Disclosures: Multiple authors have declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


  1. Deng J, Parthasarathy V, Adawi W, et al. Risk of hematologic cancer in patient with undifferentiated pruritus.  JAMA Dermatology. Published online May 25, 2022. doi:10.1001/jamadermatol.2022.1562