Lab Dept:

Anatomic Pathology

Test Name:


General Information


Muscle biopsy

CPT Codes:

Varies bases on specimen submitted and physician request:

88300 – Level I, Surgical pathology, gross examination only 88305 – Level IV - Surgical pathology, gross and microscopic examination (specific specimen types)
88313 x4 – Special Stains, Group II 88319-90 - Determinative histochemistry or cytochemistry to identify enzyme constituents, each
88319 x11 – Special stain including interpretation and report; Group III, for enzyme constituents
88348 – Electron microscopy, diagnostic

Test Includes:

A battery of histochemical stains and electron microscopy (EM) when indicated.


Test Indications:

Useful for evaluating muscle disease in terms of primary myopathy, neurogenic atrophy, etc.

Lab Testing Section:

Anatomic Pathology - Sendouts

Referred to:

Hennepin County Medical Center - Neuromuscular Lab: 612-873-2175

Phone Numbers:

MIN Lab: 612-813-6280

STP Lab: 651-220-6550

Test Availability:

Monday - Friday

Turnaround Time:

14 days

Special Instructions:

Pathology order form(s) must be filled out and submitted with specimen. Specimen needs to be in the Histology (AP) Lab by NOON, day of procedure in order to be processed and sent to HCMC. Please notify pathology laboratory 24 hours prior to specimen collection. 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 one that has been traumatized by injections or by electromyographic studies. Typically, the triceps, biceps or vastus lateralis are chosen. (We find deltoid or gastrocnemius muscles less satisfactory and more subject to artifact.)


Specimen Type:



For first two specimens: wrapped in saline-moistened gauze on wet ice.

For third specimen: muscle piece that is held at resting length by sutures on a piece of tongue blade immersed in EM fixative.

Draw Volume:

Two unfixed muscle pieces 3 - 5 mm in diameter by 1 cm in length for each specimen.

Third specimen: Muscle piece 2 mm in diameter

Processed Volume:

Same as Draw Volume


Send 2 unfixed muscle pieces, wrapped in saline-moistened gauze on wet ice. Recommended size: 3 - 5 mm in diameter by 1 cm in length for each. Send a third muscle piece that is held at resting length by sutures on a piece of tongue blade immersed in EM fixative. Recommended size: 2 mm in diameter. If biochemical studies are anticipated, additional muscle specimens must be quickly frozen and in foil, in surgery with liquid nitrogen. The frozen tissue is stored in lab’s -70 freezer until biochemical orders/requests are received.

Special Processing:

See Collection

Patient Preparation:

Physician preference

Sample Rejection:

Improperly collected specimens; mislabeled or unlabeled specimens


Reference Range:

Interpretive report


Hennepin County Medical Center Laboratory Web Page


2/12/2013: CPT update
8/11/2016: Special instructions update regarding specimen collections.