Anaplastic large-cell lymphoma (ALCL) is a rare T-cell lymphoma and typically is seen in children and young adults. Primary bone infiltration of ALCL is exceedingly rare. Herein we report ALCL of bone in a pregnant admitted with symmetric polyarthritis. Magnetic resonance imaging of the pelvis revealed soft tissue component of that destructive mass lesion on the right iliac crest after delivery. Excisional biopsy from the destructive mass showed anaplastic large cell lymphoma (CD 30 was positive and ALK negative). The patient was treated with combination chemotherapy consisting of cyclophosphamide, doxorubicin, vincristine and prednisolone (CHOP) every 4 weeks. After the third cycle of chemotherapy, a marked improvement of her arthritis and right iliac pain was noted.