The number of antibodies used per case at SJCRH ranged from 1 to 33 (average, 7.
After exclusions, the overall agreement, minor disagreement, and major disagreement rates between the referring and SJCRH diagnoses were calculated as 430 (61.
5%), the exact histopathologic nature of the lesion could not be established by the SJCRH reviewer, but the difference between original diagnosis and the final SJCRH diagnosis was sufficient to classify the cases as a major disagreement (eg, a soft tissue lesion of the distal third of left thigh: original diagnosis, high-grade sarcoma; SJCRH final diagnosis, negative for definitive neoplastic process).
6%) major disagreements (102 of 177) were equally diagnosed as malignant by the international pathologist and SJCRH pathologist, but the difference in the final diagnosis was significant enough for the case to be considered major disagreements (eg, a cerebellar tumor originally diagnosed as anaplastic ependymoma, a World Health Organization grade III tumor, but with a reviewed diagnosis of atypical teratoid-rhabdoid tumor, a World Health Organization grade IV tumor; IHC was performed in this case at the referring site and at SJCRH).
Our analysis revealed that the change from malignant diagnosis by the international pathologist to a final benign diagnosis by the SJCRH pathologist (n = 46) was three times more frequent than the change from benign to malignant (n = 15; Table 4).
The 2 cases in which SJCRH pathologist deemed IHC unnecessary in discordance with the international pathologist were (1) an original diagnosis of embryonal rhabdomyosarcoma with an SJCRH final diagnosis of fibro-osseous lesion and possible fracture with secondary aneurysmal bone cyst and no evidence of rhabdomyosarcoma in the reviewed material; and (2) an original diagnosis that included the following differential diagnosis: possible extranodal histiocytic sarcoma, synovial sarcoma, or rhabdomyosarcoma; whereas the SJCRH final diagnosis favored osteosarcoma.
3%), the SJCRH pathologist made a final diagnosis based on histomorphology alone (Table 5).
6% of major disagreement cases in which IHC was performed at the international sites (83 out of 85 cases), the use of IHC was considered necessary by SJCRH pathologists to establish a final diagnosis.
2%; Table 5), IHC was not used by the referring pathologists or the pathologist at SJCRH, and the diagnosis was based on histomorphology only.
Many international histopathologic specimens received at SJCRH for review demonstrate problems with tissue fixation, and in some cases, those problems precluded a final diagnosis.