Musculoskeletal System

Skeletal Muscle - Mineralization

Narrative
Comment:
Mineralization is histologically characterized by the presence of deeply basophilic fine to coarse granular deposits that stain positively with histochemical stains for calcium. Multinucleated foreign-body giant cells, acute or chronic inflammation, and/or a fibroblastic response may also be present. Mineralization can occur either as a result of local trauma/necrosis (dystrophic) or due to systemic Ca:P imbalances (metastatic). While dystrophic mineralization is not a common response in rats, certain mouse strains, notably BALB/c, C3H, and DBA, are particularly susceptible. Dystrophic or metastatic calcification of skeletal muscle is sporadically observed as a spontaneous change; however, diet, hormonal changes, administration of hydrocortisone, and high endogenous secretion of corticosteroids have all been postulated as contributing factors.
Recommendations:
When mineralization of skeletal muscle is significant or is a primary lesion (i.e., metastatic mineralization), it should be diagnosed and graded. Mineralization that occurs as a component of necrosis does not need to be recorded separately (unless warranted by severity) but should be described in the pathology narrative.
References:

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Greaves P. 2007. Musculoskeletal system. In: Histopathology of Preclinical Toxicity Studies, 3rd ed. Elsevier, Oxford, 160-214.

Greaves P, Seely JC. 1996. Non-proliferative lesions of soft tissues and skeletal muscle in rats, MST-1. In: Guides for Toxicologic Pathology. STP/ARP/AFIP, Washington, DC.

Greaves P, Chouinard L, Ernst H, Mecklenburg L, Pruimboom-Brees IM, Rinke M, Rittinghausen S, Thibault S, von Erichsen J, Yoshida T. 2013. Proliferative and non-proliferative lesions of the rat and mouse soft tissue, skeletal muscle, and mesothelium. J Toxicol Pathol 26(3 suppl):1S-26S.

Abstract: http://www.ncbi.nlm.nih.gov/pubmed/25035576

Leininger JR. 1999. Skeletal muscle. In: Pathology of the Mouse (Maronpot R, Boorman G, Gaul BW, eds). Cache River Press, St Louis, 637-643.

McDonald MM, Hamilton BF. 1990. Bones, joints, and synovia. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman G, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, 193-207.

Vahle JL, Leininger JR, Long PH, Hall DG, Ernst H. 2013. Bone, muscle, and tooth. In: Toxicologic Pathology: Nonclinical Safety Assessment (Sahota PS, Popp JA, Hardisty JF, Gopinath C, eds). CRC Press, Boca Raton, FL, 561-587.

Valentine BA, McGavin MD. 2007. Skeletal muscle. In: Pathologic Basis of Veterinary Disease (McGavin MD, Zachary JF, eds). Mosby Elsevier, St Louis, 973-1040.

Van Vleet JF, Valentine BA. 2007. Muscle and tendon. In: Jubb, Kennedy, and Palmer’s Pathology of Domestic Animals, 5th ed, Vol 1 (Grant MG, ed). Elsevier, Edinburgh, 185-280.

  • Image of mineralization in the skeletal muscle from a male F344/N rat in a chronic study

    Skeletal muscle - Mineralization in a male F344/N rat from a chronic study. Multiple deposits of deeply basophilic mineral are present in damaged muscle fibers.

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Skeletal muscle - Mineralization in a male F344/N rat from a chronic study. Multiple deposits of deeply basophilic mineral are present in damaged muscle fibers.

Authors

Torrie A. Crabbs, DVM, DACVP
Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC  

Reviewers

Philip H. Long, DVM, PhD, DACVP
Presiden and Senior Pathologist
Vet Path Services, Inc.
Mason, OH

Amy Brix, DVM, PhD, DACVP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC

Robert R. Maronpot, DVM, MS, MPH, DACVP, DABT, FIATP
Senior Pathologist
Experimental Pathology Laboratories, Inc.
Research Triangle Park, NC