Unilateral Arm Urticaria Presenting as a Paraneoplastic Manifestation of Metachronous Bilateral Breast Cancer.

Various paraneoplastic syndromes (PNS) are reported to be associated with breast cancer and can range from mild dermatological symptoms to severe neurological complications. Neurological and dermatological manifestations tend to be the more commonly seen paraneoplastic manifestations, albeit both are relatively rare. Diagnosis of the underlying malignancy is often delayed since the presence and severity of paraneoplastic manifestations are not dependent on the tumor size or stage. Herein, we describe a unique case of unilateral arm urticaria presenting as a paraneoplastic manifestation of metachronous bilateral breast cancer. Similar reports and other PNS associated with breast cancer are described. Recognition of PNS associated with underlying malignancies and age-appropriate screening can facilitate diagnosis of the underlying occult malignancy. Resection of the underlying malignancy can lead to resolution and/or improvement of the PNS for some patients.