Specimen Submission Guidelines for Pathologic Evaluation of Unexplained Illness due to Possibly Infectious Etiology

Download: CDC—10372 Specimen Submission Guidelines for Pathologic Evaluation of Unexplained Illness due to Possibly Infectious Etiology [PDF – 308 KB]

Unexplained critical illnesses and deaths of possible infectious etiology can be challenging cases to investigate. This is especially true for cases of sudden death, for which pre-mortem specimens are unavailable, and for cases where traditional laboratory assays have been unsuccessful in identifying a specific agent. Some of these cases have gross or histopathologic features suggestive of an infectious process, and may be submitted for evaluation by the IDPB. Performance of specific immunohistochemical, molecular, or other assays will be determined using clinical and epidemiologic information provided by the submitter and the histopathologic features identified in the submitted tissue specimens.

Collection of Tissue Specimens

Representative tissues from the major organs should be submitted for evaluation. Representative tissues should be included from all organs showing significant microscopic pathology. Preferred specimens include paraffin blocks of tissues showing gross or microscopic pathology and representative tissues in formalin (i.e. wet tissue). Fresh-frozen tissue may also be submitted for culture and molecular-based assays.

Submission of Specimens

Paraffin-embedded tissue blocks

In general, this is the preferred specimen and is especially important to submit in cases where tissues have been in formalin for a significant time. Prolonged fixation (>2 weeks) may interfere with some immunohistochemical and molecular diagnostic assays.

Wet tissue

If available, we highly recommend that unprocessed tissues in 10% neutral buffered formalin be submitted in addition to paraffin blocks.

Unstained slides

Although not optimal, if paraffin blocks are unavailable it may be possible to utilize unstained sections cut at 3–5 microns (10 slides per block) for immunohistochemistry and special stains but not molecular diagnostic assays (e.g. PCR).

Fresh-frozen tissue

Send separately on dry ice.

Electron Microscopy (EM) specimens

Samples fixed in glutaraldehyde and held in phosphate buffer. Sample containers are filled to the top with phosphate buffer and sent on wet ice. Do not freeze. Epoxy-embedded tissues are also accepted.

Please refer to our General Guidelines for shipping pathology specimens.