pseudohypertrophy

{{Hatnote| Not to be confused with Pseudoathletic appearance which can include pseudohypertrophy, but also hypertrophy among other pathological forms of enlargement}}

{{Short description|False enlargement of muscle due to infiltration of fat or other tissue}}

{{Infobox medical condition

|name = Pseudohypertrophy

|synonym = false enlargement

|image = File:Drawing of boy with Duchenne muscular dystrophy.png

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|caption = Drawing of seven-year-old boy with Duchenne muscular dystrophy. There is pseudohypertrophy of the lower limbs.

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|symptoms = Weakness

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|causes = muscle disease, nerve disease

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Pseudohypertrophy, or false enlargement, is an increase in the size of an organ due to infiltration of a tissue not normally found in that organ.{{cite book |last1=Adami |first1=John George |title=The Principles of pathology |date=1908 |page=540 |edition=1 |url=https://books.google.com/books?id=qrHDcwk0HVcC&dq=pseudohypertrophy+etymology&pg=PA540 |access-date=23 April 2022}} It is commonly applied to enlargement of a muscle due to infiltration of fat or connective tissue,{{cite journal |last1=Walters |first1=J |title=Muscle hypertrophy and pseudohypertrophy. |journal=Practical Neurology |date=October 2017 |volume=17 |issue=5 |pages=369–379 |doi=10.1136/practneurol-2017-001695 |pmid=28778933|s2cid=6444771 |doi-access=free }} famously in Duchenne muscular dystrophy. This is in contrast with typical muscle hypertrophy, in which the muscle tissue itself increases in size. Because pseudohypertrophy is not a result of increased muscle tissue, the muscles look bigger but are actually atrophied and thus weaker.{{Cite journal |last=Tyler |first=Frank H. |date=1950-03-01 |title=STUDIES IN DISORDERS OF MUSCLE: III. "Pseudohypertrophy" of Muscle in Progressive Muscular Dystrophy and Other Neuromuscular Diseases |url=http://archneurpsyc.jamanetwork.com/article.aspx?doi=10.1001/archneurpsyc.1950.02310210071005 |journal=Archives of Neurology & Psychiatry |language=en |volume=63 |issue=3 |pages=425 |doi=10.1001/archneurpsyc.1950.02310210071005 |issn=0096-6754|url-access=subscription }} Pseudohypertrophy is typically the result of a disease, which can be a disease of muscle or a disease of the nerve supplying the muscle.

Causes of pseudohypertrophy include muscle diseases: dystrophinopathies, limb-girdle muscular dystrophies, metabolic myopathy, Dystrophic myotonias, Non-dystrophic myotonias, endocrine disorders, parasitic muscle conditions, amyloid and sarcoid myopathy, and granulomatous myositis.

Neurological causes include radiculopathy, poliomyelitis, Charcot-Marie-Tooth disease, spinal muscular atrophy.

In pseudohypertrophy where the atrophied muscle tissue has been infiltrated by fat tissue, upon palpitation the seemingly large muscles feel doughy.

Not all muscles infiltrated by fat or other tissue are pseudohypertrophic. In muscular steatosis, sometimes the muscles may appear a normal or a slender size, even though the atrophied muscle has been infiltrated with fat tissue, such as the calf muscles in Bethlem myopathy 1.{{Cite journal |last1=Nalini |first1=A. |last2=Gayathri |first2=N. |date=2010-07-01 |title=Bethlem myopathy: A study of two families |url=https://www.neurologyindia.com/article.asp?issn=0028-3886;year=2010;volume=58;issue=4;spage=665;epage=666;aulast=Nalini;type=0 |journal=Neurology India |language=en |volume=58 |issue=4 |pages=665–666 |doi=10.4103/0028-3886.68684 |issn=0028-3886 |pmid=20739820 |doi-access=free |url-access=subscription }}{{Cite journal |last=Bönnemann |first=Carsten G. |date=2011-06-21 |title=The collagen VI-related myopathies: muscle meets its matrix |journal=Nature Reviews. Neurology |volume=7 |issue=7 |pages=379–390 |doi=10.1038/nrneurol.2011.81 |issn=1759-4766 |pmc=5210181 |pmid=21691338}}{{Cite journal |last1=Suh |first1=B.C. |last2=Choi |first2=Y.C. |last3=Kim |first3=S.M. |last4=Choi |first4=B.O. |last5=Shim |first5=D. |last6=Lee |first6=D.H. |last7=Sunwoo |first7=I. |date=2006 |title=A Family of Bethlem Myopathy |journal=Journal of the Korean Neurological Association |volume=24 |pages=614–617|s2cid=74251729 }}{{Cite journal |last1=Souza |first1=Paulo Victor Sgobbi de |last2=Bortholin |first2=Thiago |last3=Pinheiro |first3=Jhonatan Rafael Siqueira |last4=Naylor |first4=Fernando George Monteiro |last5=Pinto |first5=Wladimir Bocca Vieira de Rezende |last6=Oliveira |first6=Acary Souza Bulle |date=2017-10-01 |title=Collagen type VI-related myopathy |url=https://pn.bmj.com/content/17/5/406 |journal=Practical Neurology |language=en |volume=17 |issue=5 |pages=406–407 |doi=10.1136/practneurol-2017-001661 |issn=1474-7758 |pmid=28578317|url-access=subscription }}{{Cite journal |last1=Telles |first1=Juliana Aparecida Rhein |last2=Voos |first2=Mariana Calil |last3=Anequini |first3=Isabella Pessa |last4=Favero |first4=Francis Meire |last5=Silva |first5=Thiago Henrique |last6=Caromano |first6=Fátima Aparecida |date=June 2018 |title=Genetic and functional differences between Bethlem myopathy and Ullrich congenital muscular dystrophy - case studies |url=http://pepsic.bvsalud.org/scielo.php?script=sci_abstract&pid=S1519-03072018000100009&lng=pt&nrm=iso&tlng=en |journal=Cadernos de Pós-Graduação em Distúrbios do Desenvolvimento |language=en |volume=18 |issue=1 |pages=148–163 |doi=10.5935/cadernosdisturbios.v18n1p148-163 |issn=1519-0307|url-access=subscription }} In myosclerosis, the muscle is infiltrated with connective tissue and fibrosis, having a firm, "woody" feel upon palpitation, with the muscles appearing slender.{{Cite journal |last1=Bradley |first1=W. G. |last2=Hudgson |first2=P. |last3=Gardner-Medwin |first3=D. |last4=Walton |first4=J. N. |date=August 1973 |title=The syndrome of myosclerosis |journal=Journal of Neurology, Neurosurgery, and Psychiatry |volume=36 |issue=4 |pages=651–660 |doi=10.1136/jnnp.36.4.651 |issn=0022-3050 |pmid=4793163|pmc=494424 }}{{Cite journal |last1=Merlini |first1=L. |last2=Martoni |first2=E. |last3=Grumati |first3=P. |last4=Sabatelli |first4=P. |last5=Squarzoni |first5=S. |last6=Urciuolo |first6=A. |last7=Ferlini |first7=A. |last8=Gualandi |first8=F. |last9=Bonaldo |first9=P. |date=2008-10-14 |title=Autosomal recessive myosclerosis myopathy is a collagen VI disorder |url=https://pubmed.ncbi.nlm.nih.gov/18852439/ |journal=Neurology |volume=71 |issue=16 |pages=1245–1253 |doi=10.1212/01.wnl.0000327611.01687.5e |issn=1526-632X |pmid=18852439}}