Primary bone lymphomas thought to be osteomyelitis urgently demand a rapid diagnosis in bone pathology.

We describe in detail three cases of primary bone lymphoma (PBL), initially treated as osteomyelitis of unknown etiology. These cases show which difficulties can occur with diagnosing this entity and highlight the urgent need for rapid diagnostic results in the field of bone pathology. Case 1: A 22-year-old man with the very rare diagnosis of precursor B-lymphoblastic lymphoma in the tibia (previously published). Case 2: A 13-year-old boy with an anaplastic large cell lymphoma of the "os pubis". With initial diagnosis pointing to multifocal osteomyelitis, histology of the left iliac crest revealed a florid/chronic osteomyelitis. During clinical regression with a new osteolytic lesion, he received treatment for chronic recurrent multifocal osteomyelitis. Case 3: A 60-year-old man with an anaplastic large cell lymphoma of the right sacrum, accompanied by a putrid, florid/chronic osteomyelitis. At first, an incisional biopsy revealed a florid/chronic osteomyelitis-only.