The histology in Figure E is most consistent with an osteoid osteoma.
Osteoid osteomas are benign bone forming neoplasms that are characterized by their small size (less than 2 cm) and self-limited growth. They occur most commonly in adolescence and have a slight male predominance. The lesion classically presents with severe pain at night that is dramatically relieved by NSAIDs. The tumor has been shown to express very high levels of prostaglandins, particularly PGE2 and PGI2, which are presumed to be the cause of the intense pain seen in patients with this lesion.
Mungo et al. investigated the role of cyclooxygenases in the production of prostaglandins in osteoid osteomas. They found strong immunohistochemical staining for COX-2 in osteoid osteomma surgical samples. They conclude that the increased production of prostaglandins by osteoid osteomas implicates that COX-2 is one of the mediators of this condition. For this reason, they hypothesize that selective that COX-2 inhibitors could be used to more safely treat osteoid osteomas.
Rosenthal et al. compared percutaneous radiofrequency coagulation with operative treatment in patients with osteoid osteomas. They found percutaneous ablation with radiofrequency is equivalent to operative excision for the treatment of an osteoid osteoma in an extremity. They suggest the percutaneous method is preferred for the treatment of extraspinal osteoid osteoma because it does not necessitate hospitalization, has decreased complications, and leads to a quicker recovery time.
Figure E shows the characteristic findings of an osteoid osteoma which includes woven bone surrounded by osteoblasts, without neoplastic cells or cellular atypia. Illustration A shows a high powered view of osteosarcoma. Notice the high nuclear to cytoplasmic ratio with cellular atypia of the neoplasmic stromal cells
Answer 1: Figure A shows hypocellular with bland hyaline cartilage consistent with an enchondroma.
Answer 2: Figure B is a chordoma given the diagnostic clear physaliphorous cells.
Answer 3: Figure C is a high grade osteosarcoma as can be seen with the woven bone and the high nuclear to cytoplasmic ratio with cellular atypia of the neoplasmic stromal cells.
Answer 4: Figure D is normal lung tissue.
Mungo DV, Zhang X, O'Keefe RJ, Rosier RN, Puzas JE, Schwarz EM. COX-1 and COX-2 expression in osteoid osteomas. J Orthop Res. 2002 Jan;20(1):159-62. PubMed PMID: 11853083.
PMID:11853083 (Link to Abstract)
Rosenthal DI, Hornicek FJ, Wolfe MW, Jennings LC, Gebhardt MC, Mankin HJ. Percutaneous radiofrequency coagulation of osteoid osteoma compared with operative treatment. J Bone Joint Surg Am. 1998 Jun;80(6):815-21. PubMed PMID: 9655099.
PMID:9655099 (Link to Abstract)