Section 493.1273 - [Effective until 12/28/2024] Standard: Histopathology(a) As specified in § 493.1256(e)(3) , fluorescent and immunohistochemical stains must be checked for positive and negative reactivity each time of use. For all other differential or special stains, a control slide of known reactivity must be stained with each patient slide or group of patient slides. Reaction(s) of the control slide with each special stain must be documented.(b) The laboratory must retain stained slides, specimen blocks, and tissue remnants as specified in § 493.1105 . The remnants of tissue specimens must be maintained in a manner that ensures proper preservation of the tissue specimens until the portions submitted for microscopic examination have been examined and a diagnosis made by an individual qualified under § 493.1449(b), (l), or (m) .(c) An individual who has successfully completed a training program in neuromuscular pathology approved by HHS may examine and provide reports for neuromuscular pathology.(d) Tissue pathology reports must be signed by an individual qualified as specified in paragraph (b) or, as appropriate, paragraph (c) of this section. If a computer report is generated with an electronic signature, it must be authorized by the individual who performed the examination and made the diagnosis.(e) The laboratory must use acceptable terminology of a recognized system of disease nomenclature in reporting results.(f) The laboratory must document all control procedures performed, as specified in this section. 68 FR 3703 , Jan. 24, 2003; 68 FR 50724 , Aug. 22, 2003