Abstract
Selective immunoglobin A deficiency (IgAD) is the most common immunodeficiency disorder in the western world. Cancer is the most common cause of death in these individuals. Various cases have been reported of squamous cell carcinoma (SCC) in IgAD at sites like skin, oral cavity, and lung. Here we present a rare case of SCC occurring as anal cancer. No other reports to our knowledge describe this rare presentation. A 54-year-old Caucasian woman with asymptomatic partial IgAD presented with a palpable anal mass. Further evaluation showed stage IIIa SCC anal cancer (T1N1M0). Additional workup showed positive human papilloma virus (HPV) serology and positive HPV immunohistochemistry studies. The patient achieved complete response with chemoradiation with her most recent imaging and anorectal exam showing no evidence of cancer recurrence at 3 years follow-up. This case highlights the association between IgAD and malignancy. Although IgAD is the most common primary antibody deficiency, this patient's case presents a rare instance of anal SCC in an IgA-deficient individual. Studies show an association between HPV infection and SCC, but few include IgA-deficient individuals. Patients with IgAD and other immunodeficiencies are at higher risk for HPV infection and therefore may be at a higher risk of SCC. With widespread use of the HPV vaccine, the medical community should be aware of its importance in cancer prevention for these patients. Further studies are needed to evaluate relationships between IgAD, HPV infections, SCC cancer, and the role that the HPV vaccine has in cancer prophylaxis.