Soft Tissue Tumors - Intramuscular lipoma

Home Chapter Home Jobs Conferences Fellowships Books

Soft Tissue Tumors

Adipose tissue

Intramuscular lipoma

Reviewer: Charanjeet Singh, M.D. (see Reviewerspage)
Revised: 10 November 2012, last major update June 2012
Copyright: (c) 2003-2012, PathologyOutlines.com, Inc.

General
=========================================================================

● Lipoma that infiltrates within muscle belly
● Called intermuscular lipoma if between muscle fascicles

Terminology
=========================================================================

● Also called invasive or infiltrative lipoma
● Not a WHO diagnosis

Sites
=========================================================================

● Intramuscular: affects thigh, trunk, head and neck of middle-aged adults
● Intermuscular: affects abdominal wall of middle-aged adults; doesn’t recur if completely excised

Clinical features
=========================================================================

● Benign, but 20% recur due to incomplete excision
● Infiltration may be due to muscular degeneration and endomysial fatty growth secondary to atrophy (BMC Musculoskelet Disord 2004;18:20)

Case reports
=========================================================================

● 37 year old woman with giant infiltrative tumor of face (AJNR Am J Neuroradiol 2003;24:283)
● 58 year old and 63 year old women with tumors of pectoralis major muscle simulating a breast mass (Ann Acad Med Singapore 2005;34:275, Arch Pathol Lab Med 2011;135:1061)
● Well circumscribed tumor of sternocleidomastoid muscle (Auris Nasus Larynx 2004;31:283)

Clinical images
=========================================================================

Tumor of face

Gross description
=========================================================================

● Intramuscular - poorly circumscribed, extends between and around skeletal muscle fibers

Gross images
=========================================================================

Yellow adipose tissue within skeletal muscle

Irregular lobulated tumor without encapsulation

Deep tumor of calf

Other images: yellow adipose tissue within skeletal muscle

Micro description
=========================================================================

● Mature lipocytes that infiltrate skeletal muscle
● No atypia, no mitotic figures

Micro images
=========================================================================

Prominent muscular atrophy

Adipocytes and atrophic muscle

Intramuscular lipoma

Other images: intramuscular fat tissue covered by fibrous capsule

Differential diagnosis
=========================================================================

● Intramuscular hemangioma: adolescents and young adults, usually head and neck, prominent vasculature, variable adipose tissue
● Well differentiated liposarcoma: definite atypia present

End of Soft Tissue Tumors > Adipose tissue > Intramuscular lipoma

This information is intended for physicians and related personnel, who understand that medical information is often imperfect, and must be interpreted in the context of a patient's clinical data using reasonable medical judgment. This website should not be used as a substitute for the advice of a licensed physician.

All information on this website is protected by copyright of PathologyOutlines.com, Inc. Information from third parties may also be protected by copyright. Please contact us at copyrightPathOut@gmail.comwith any questions (click here for othercontact information).