Human skeletal muscles replaced to a high degree by white adipose tissue

Abstract

Summary: Extreme replacement of skeletal muscles by adipose tissue was found in an 86-year old Japanese male cadaver during dissection practice for medical students at Oita University School of Medicine. Especially, the bilateral sartorius muscles looked overall like adipose tissue. The man had suffered from diabetes mellitus, renal failure, hypertension and hypothyroidism before his death. He was also an alcohol drinker. He had been bedridden late in life. The cause of death was renal failure. In microscopy, the adipose tissue-like sartorius muscle was shown to consist of leptin-positive adipocytes with a small number of degenerated muscle fibers. Fatty replacement, or fatty degeneration, appears to result from endocrine and metabolic disorders, and being bedridden leads to muscle atrophy and damage, although the origin of the adipocytes which emerged in the degenerated muscles is unknown.

Complete Adipose Replacement of Bilateral Medial Gastrocnemius Muscle - A Cadaveric Case Report

“…The author thought that adipose replacement or degeneration of the sartorius muscles appeared to result from possible medical history and bedridden status that could lead to muscle atrophy and damage, consequently the sarcopenia. [11] In our present case, the cause of death was advanced dementia, which could cause a bedridden status and inactivity, which accordingly could lead to increased IMAT in the GM . [1,10] Embryologically, skeletal muscles, including the GM, derive from the paraxial mesoderm.…”

“…[8][9][10] It matched well with the cadaveric case report of adipose tissue deposit as the IMAT in the whole bilateral sartorius muscles at the anteromedial thigh of an 86-year old male. [11] In comparison, our cadaveric case appears to have a similar pattern of adipose depositionentire fatty replacement of bilateral medial gastrocnemius muscles. Literature has exerted that adipocytes exist in skeletal muscles and the number of these cells can increase if the muscle is injured.…”

“…To our knowledge, this case is second time showing a bilateral symmetric muscles replaced entirely by adipose tissue. In 2011, Ina et al, [11] observed bilateral sartorius muscles replaced by white adipose tissue and the whole muscle appeared as fat on an 86-year-old Japanese male cadaver during regular dissection for medical students. In this case, [11] the male donor was bedridden during his late life and cause of death was renal failure.…”

“…In 2011, Ina et al, [11] observed bilateral sartorius muscles replaced by white adipose tissue and the whole muscle appeared as fat on an 86-year-old Japanese male cadaver during regular dissection for medical students. In this case, [11] the male donor was bedridden during his late life and cause of death was renal failure. The author thought that adipose replacement or degeneration of the sartorius muscles appeared to result from possible medical history and bedridden status that could lead to muscle atrophy and damage, consequently the sarcopenia.…”

“…So, we are in agreement with the previous case speculating that the origin of adipocytes in the muscles replaced by fat might be from mesenchymal progenitors in muscle tissue. [11] Studies have demonstrated that the lower extremity, particularly the thigh area, is a common for the IMAT. [8][9][10] It matched well with the cadaveric case report of adipose tissue deposit as the IMAT in the whole bilateral sartorius muscles at the anteromedial thigh of an 86-year old male.…”