Isolated pauciimmune pulmonary capillaritis successfully treated with rituximab.

Diffuse alveolar hemorrhage (DAH) is a syndrome caused by different mechanisms, including capillary stress failure, diffuse alveolar damage, and capillaritis. Capillaritis is the most common cause and is often associated with systemic autoimmune disorders, most commonly antineutrophilic cytoplasmic antibody-associated vasculitis. The occurrence of DAH with underlying pulmonary capillaritis but without clinical or serologic findings of an associated underlying systemic disorder is known as isolated pauciimmune pulmonary capillaritis (IPPC), and only eight cases have been described in the literature. The mainstay of treatment of this rare condition has been cyclophosphamide and glucocorticoids. When cases are unresponsive to cyclophosphamide, there is no known alternative treatment. Herein, we describe a case of IPPC that failed cyclophosphamide treatment with recurrent DAH. Rituximab therapy was then initiated with no further evidence of recurrence. This case report suggests that rituximab could be considered an alternative therapy to induce remission in patients with IPPC.