This group is predominantly "small blue cell tumors": neuroblastoma, primitive neuroectodermal tumor (PNET), Ewing’s sarcoma, rhabdomyosarcoma, synovial sarcoma, desmoplastic small round cell tumor and lymphoblastic lymphomas. These tumors need to be handled following special institutional guidelines / protocols.
Expedient collection and triage of fresh tissue is important
Measure (three dimensions), weigh, photograph, and orient (if margins are designated by the surgeon) and ink the resection margins of the specimen.
Obtain the following for all pediatric tumors which are received without fixative (if there is tissue in excess of what is needed for histologic diagnosis) (see diagram below):
Cytogenetics: take 0.25 - 1 gm of sterile tumor in RPMI or other cell culture medium at room temperature. Rationale: this may be the most diagnostic study. Small round cell tumors are very fragile, and culture needs to be started within 2-3 hours of tissue receipt in pathology.
Molecular analysis: 100 mg to 1 g of tumor and 100 mg to 1 g of non-tumor tissue (labeled as such and collected in separate containers) frozen at -20°C (can use cryostat) and then transferred to -80°C or liquid nitrogen tank. This will be held in reserve, as it will be especially important if cytogenetics does not have a successful culture.
Electron microscopy: 2 x 2 x <1 mm of tumor in glutaraldehyde for EM block and hold. This is particularly valuable for some renal tumors.
Flow cytometry: 100 mg to 1 g of tumor in RPMI or other cell culture medium if it is a small round cell tumor, making leukemia or lymphoma a concern.
Tumor bank: 100 mg to 1 g of tumor and 100 mg to 1 g of non-tumor tissue (labeled as such and collected in separate containers) frozen at -20°C.
Measure (three dimensions) and describe the tumor (color, consistency, shape). Measure the distance from the margin.
Determine the optimal way to section the specimen, as this will vary from case to case depending on site, specimen size, and type of resection. Make tumor cuts that will allow for the best evaluation of margins. Take margin sections first, then take representative sections of tumor.
Consult with the attending pathologist about pre-ordering unstained sections on tumor blocks for immunohistochemistry. This may expedite the final reporting.