Pulmonary coccidiomycosis masquerading as refractory metastatic Ewing sarcoma.

We report the case of a patient who presented with a large pelvic mass, which was biopsy-proven to be Ewing sarcoma. The patient was also found to have 18 pulmonary lesions on a staging CT that were presumed to represent metastatic disease. After induction chemotherapy, a PET/CT scan revealed a marked reduction in his pelvic mass along with improvement in nearly all his pulmonary lesions except 2, which increased in size. The mixed response to chemotherapy was unusual and the decision was made to resect one of the growing lesions. Fungal culture from the excised lesion grew Coccidioides immitis.