Guidelines for Tissue Biopsy including Muscle Biopsy
1- Specimen Preparation for Tissue Biopsy
Tissue specimens should be immersed in the fixative labeled formalin, which is provided. The ratio of fluid to tissue, ideally, is 10:1. For larger specimens use an appropriate size of container. Sizes provided are 20 ml and 120ml. Fixation should be prompt. This includes skin and GYN specimen. For testicular biopsy, Bovin’s solution is preferred but is not absolute. Ask from Delta Lab customer service for this fixative.
2- Preparation of Muscle Biopsy for Enzyme Histochemistry
Obtain the biopsy from a muscle that is definitely affected but not so severely affected that much of it is replaced by fatty or fibrous connective tissue. In addition, the involved muscle should not be the one that has been traumatized by injections or by electromyographic studies. Typically, the triceps, or vastus lateral are chosen. Deltoid or gastrocnemius muscles are less satisfactory and more prone to artifact.
Excise a specimen approximately 1.0 cm with minimal trauma by dissecting along the long axis of the muscle. Immediately, after removal,. The specimen must be fresh-frozen. Plunge the specimen into a slurry of dry ice and absolute alcohol. It is important that at least 80% of the slurry should be dry ice. The slurry must be stirred constantly to assure that a uniform temperature of –70 °C is achieved. The immersion into the freezing solution is to last not more than is needed to completely freeze the specimen. During the period of immersion the specimen should be swirled around in the slurry. The well-frozen specimen has a white chalky color. Prolonged immersion in the quenching mixture should be avoided, as the specimen can become permeated by alcohol or acetone. The total freezing time is usually <10 sec. Immediately, after this, the frozen specimen is removed and packed in dry ice or temporarily stored at –70 °C. Send specimen FROZEN on dry ice.
Estrogen and Progesterone Receptors Assay
1- A Note on Estrogen-Progesterone Binding Receptor Sites
The presence of steroid receptor sites on certain tumors has been correlated with improved prognosis. In patients with breast cancer, endometrial cancer, or endometrioid carcinoma of the ovary, levels of estrogen receptor sites and progesterone receptor sites have been correlated with an improved response to estrogen therapy. These receptor sites are more likely to be present in menopausal patients. Seventy percent tumors with estrogen receptors regress after hormonal manipulation, whereas only 5% of those that are negative respond to this treatment.
Steroid receptor hormones usually have been measured on fresh tissue using a radioactive ligand binding on cytosol preparations. This method was difficult to control because of lack of information on the amount of tumor tissue versus normal tissue. Specimens were transported frozen, which was inconvenient and risked inaccurate results. With the development of antibodies to steroid receptor sites it became possible to perform analyses on tissue on tissue slides-both frozen sections and paraffin-embedded sections. Clinical studies have now shown that tissue sections stained by the immunoperoxidase technique give results with the same clinical significance as with fresh-tissue cytosol method. Delta’s Lab reference laboratory, we use the immunoperoxidase technique on paraffin-embedded tissue.
2- Specimen Preparation:
Submit four unstained slides or a formalin-fixed tissue block containing areas of well-preserved tumor. The tissue should be fixed in neutral-buffered formalin for a minimum of 6 hours and a maximum of 18 hours. The formalin should be less than one month old. If the tissue cannot be immediately embedded, place in 70% ethanol for storage after 18 hours in formalin.
The results of estrogen and progesterone receptor assays are reported as positive or negative for receptor sites. A positive result shows at least 20% of tumor cells stain for receptor sites.