Pseudoathletic appearance

Pseudoathletic appearance is a medical sign meaning to have the false appearance of a well-trained athlete due to pathologic causes (disease or injury) instead of true athleticism. It is also referred to as a Herculean or bodybuilder-like appearance. It may be the result of muscle inflammation (immunity-related swelling), muscle hyperplasia, muscle hypertrophy, muscle pseudohypertrophy (muscle atrophy with infiltration of fat or other tissue), or symmetrical subcutaneous (under the skin) deposits of fat or other tissue.

The mechanism resulting in this sign may stay consistent or may change, while the sign itself remains. For instance, some individuals with Duchenne and Becker muscular dystrophy may start with true muscle hypertrophy, but later develop into pseudohypertrophy.

In healthy individuals, resistance training and heavy manual labour creates muscle hypertrophy through signalling from mechanical stimulation (mechanotransduction) and from sensing available energy reserves (such as AMP through AMP-activated protein kinase); however, in the absence of a sports or vocational explanation for muscle hypertrophy, especially with accompanying muscle symptoms (such as myalgia, cramping, or exercise intolerance), then a neuromuscular disorder should be suspected.

As muscle hypertrophy is a response to strenuous anaerobic activity, ordinary everyday activity would become strenuous in diseases that result in premature muscle fatigue (neural or metabolic), or disrupt the excitation-contraction coupling in muscle, or cause repetitive or sustained involuntary muscle contractions (fasciculations, myotonia, or spasticity). In lipodystrophy, an abnormal deficit of subcutaneous fat accentuates the appearance of the muscles, though in some forms the muscles are quantifiably hypertrophic (possibly due to a metabolic abnormality).

Diseases

Skeletal muscle

+Disease groupingDiseaseMuscle(s) typically affectedAge of onsetBiopsy, ultrasonography, CT scan or MRI Hyperplasia Myostatin-related muscle hypertrophy (MSTN gene)GeneralPrenatal-onsetMyofibre hyperplasia and decreased adipose tissue.Beckwith–Wiedemann syndromeMacroglossia /hemihypertrophy of limb or bodyPrenatal to infantile-onsetWide phenotypic variability. Macroglossia (enlarged tongue) and hemihyperplasia (enlargement on one side of the body) in general or an isolated limb.Aberrant muscle syndrome (congenital muscular hyperplasia of the hand and/or foot)

(PIK3CA-related overgrowth spectrum)Hand and/or footChildhood-onsetMuscle hyperplasia and ectopic (out of place) striated muscle fibres in dermis and hypodermis.ParasiticDisseminated muscular cysticercosis syndromeGeneral /calf muscleVariablePork tapeworm cystsTrichinosisGeneralVariableSkeletal muscle inflammation (myositis) secondary to roundworm cysts and larvae.InflammationInflammatory myopathies (Focal myositis, polymyositis, granulomatous myositis, inclusion body myositis)Calf muscle/generalSarcoid granulomas/SarcoidosisCalf muscle/generalInflammatory cells and deposits of sarcoid granulomasAmyloid deposits/Amyloidosis (Inflammatory protein serum amyloid A, or in association with inflammatory diseases)Calf muscle/generalAmyloid depositsOssificationFibrodysplasia ossificans progressiva (formerly known as myositis ossificans progressiva)GeneralEpisodic inflammatory flare-ups involving skeletal muscle (myositis) secondary to muscle tissue turning into bone (ossification)Non-hereditary myositis ossificans GeneralEpisodic inflammatory flare-ups involving skeletal muscle (myositis) secondary to muscle tissue turning into bone (ossification)Muscular dystrophyDuchenne muscular dystrophyCalf muscle /generalChildhood-onsetMuscle hypertrophy may precede pseudohypertrophy by infiltration of fatty tissueBecker muscular dystrophyCalf muscle /generalVariableMuscle hypertrophy may precede pseudohypertrophy by infiltration of fatty tissueFacioscapulohumeral muscular dystrophyCalf muscle/infraspinatus /deltoid muscles"Poly-hill sign" (hypertrophy and atrophy of shoulder girdle muscles) and "Popeye sign" (atrophy of biceps, but spared forearm).Myotonic dystrophy types 1 & 2Calf muscleVariableVariable. Calf muscle hypertrophy rare in type 1, EMG showing persistent myotonic discharges in affected muscles. Calf muscle hypertrophy common in type 2 (about 50%), EMG may be normal or show myotonic discharges. Limb-girdle muscular dystrophy (LGMD) types R1 (formerly, 2A), R3 (2D), R4 (2E), R5 (2C), R6 (2F), R7 (2G), R8 (2H), R9 (2I), R10 (2J), R11 (2K), R12 (2L), R13 (2M), R14 (2N), R15 (2O), R16 (2P), R19 (2T), R20 (2U), R23, R24, R26, R28 Calf muscle /macroglossia /generalVariableHypertrophy and/or pseudohypertrophy by fatty infiltration of muscle. Classic dystrophic changes include myonecrosis and regeneration, variations in muscle fibre size, myofibrosis, fatty infiltration.

LGMD1H shows histochemical evidence suggestive of a mitochondrial myopathy and since 2017 was excluded from LGMD (see below under metabolic myopathy).Muscular dystrophy-dystroglycanopathy (MDDG) (types A2, A4, B1, B2, B5, B6, C2, C3, C4, C5, C7, C8, C9, C12, C14) Calf muscleHypertrophy and/or pseudohypertrophy by fatty infiltration of muscle.Myopathy, X-linked, with postural muscle atrophy (formerly Emery–Dreifuss muscular dystrophy 6, X-linked)Proximal musclesVariable (late childhood to adult-onset)Muscle hypertrophy precedes muscle atrophy. Biopsy shows myopathic or dystrophic changes, rimmed vacuoles, cytoplasmic bodies, and granulofilamentous material.Emery–Dreifuss muscular dystrophy 2, autosomal dominant (EDMD2) (formerly, LGMD1B)Calf muscleChildhood-onsetCalf muscle hypertrophy. Biopsy shows neurogenic and myopathic changes, including fibre type variation, central nuclei, fibrosis and fatty infiltration. EMG myopathic. Miyoshi muscular dystrophy 3Calf muscles /extensor digitorum brevis musclesAdult-onsetMuscle hypertrophy and/or pseudohypertrophy by infiltration of fatty tissue. Muscle hypertrophy precedes muscle atrophy.Myopathy, vacuolar, with CASQ1 aggregatesCalf muscleAdolescence to adult-onsetCalf muscle hypertrophy in some. Muscle biopsy shows vacuoles predominantly in type II (fast-twitch/glycolytic) fibres, rare necrotic fibres, CASQ1-immunopositive inclusions, decreased density of calcium release units, abnormal sarcoplasmic reticulum elements, enlarged terminal cisternae of the sarcoplasmic reticulum, and enlarged vesicles of sarcoplasmic reticulum origin.Myofibrillar myopathy 3 (MFM3) (MYOT gene, Ser55Phe missense mutation phenotype)

(formerly, LGMD1A)Neck, trunk, thigh and leg musclesAdult-onsetPseudohypertrophy by infiltration of fatty tissue. Muscle biopsy showed myofibrillar myopathy with prominent protein aggregates, type I (slow-twitch/oxidative) fibre predominance, other abnormalities. EMG myopathic with spontaneous activity at rest, with or without complex repetitive discharges. Muscles felt stiff upon palpitationMyofibrillar myopathy 8 (MFM8) (PYROXD1 gene)Rectus femoris/calf muscleVariableHypertrophy and/or pseudohypertrophy by infiltration of fatty tissue. Fatty atrophy of muscle common, except the rectus femoris (a thigh muscle) commonly spared or hypertrophic. Pseudohypertrophy of calf muscles. EMG myopathic. Muscle biopsy commonly showed dystrophic changes, myofibrillar inclusions, nemaline rods, internalized nuclei, other myopathic features.Myofibrillar myopathy 9 with early respiratory failure (MFM9)Calf muscleVariable adult-onset (20s-70s)Calf muscle hypertrophy. EMG myopathic. Muscle biopsy myopathic or dystrophic changes with fibre splitting, eosinophilic cytoplasmic inclusions consistent with myofibrillar myopathy, rimmed vacuoles, and increased connective or fatty tissue.Myofibrillar myopathy 10 (MFM10)Trapezius and latissimus dorsi muscles Childhood to young adult-onsetHypertrophic neck and shoulder girdle muscles. Muscle biopsy shows structural abnormalities, lobulated type I (slow-twitch/oxidative) muscle fibres, irregular intermyofibrillar network, autophagic vacuoles with lipoprotein deposits, and sarcolemmal abnormalities.Myofibrillar myopathy 11 (MFM11)Calf muscleChildhood-onsetPseudohypertrophic calf muscles (mild fatty infiltration seen on MRI). Biopsy shows type I (slow-twitch/oxidative) fibre predominance, centralized nuclei, core-like lesions, abnormal myofibrillar aggregates or inclusions. EMG myopathic.Myopathy, distal, Tateyama type (MPDT)Calf muscleChildhood to young adult onsetHypertrophic calf muscles. Atrophy in muscles of hands and feet. Biopsy shows internal nuclei, absence of CAV3 staining, mild variation in fibre size, type I (slow-twitch/oxidative) fibre type predominance. EMG myopathic, low amplitude and short duration MUAPs. Myopathy, distal, infantile-onsetCalf muscleInfantile-onsetHypertrophic calf muscles. Biopsy shows fibre size variation, increased internal nuclei, degenerating fibres, increased connective tissue and fat. EMG myopathic in affected muscles, normal in peroneal (outer calf) muscles.Muscular dystrophy, autosomal recessive, with cardiomyopathy and triangular tongue (MDRCMTT) (formerly, LGMD2W)Calf muscle and macroglossiaChildhood-onsetHypertrophic calf muscles and enlarged tongue with a small tip (triangle tongue). Biopsy shows dystrophic features with fibre size variation, necrotic fibres, scattered fibrosis and fatty infiltration.Non-dystrophic myotonias and pseudomyotonias (delayed muscle relaxation)Myotonia congenita (Chloride channelopathy, CLCN1 gene)Calf muscle /generalCalf muscle hypertrophy.Potassium-aggravated myotonia, paramyotonia congenita (Sodium channelopathy, SCN4A gene)Calf muscle /generalMuscle hypertrophy.Brody disease (formerly, Brody myopathy)Calf muscleVariable Commonly marked variability of muscle fibre size, type II (fast-twitch/glycolytic) muscle fibres may be abnormally increased or decreased, usually increased internal nuclei, rarely nuclear centralization or nuclear clumping. Muscle activity is electrically silent on EMG.Rippling muscle disease (RMD) types 1 & 2 (RMD2 formerly, LGMD1C)Calf muscle /generalMuscle hypertrophy. Muscle activity is electrically silent on EMG.LipodystrophyFamilial partial lipodystrophy (Köbberling–Dunnigan syndrome)Calf muscle /generalAdolescence-onsetHypertrophy of calf musclesCongenital generalized lipodystrophy (Berardinelli–Seip syndrome)GeneralInfantile-onsetMuscle hypertrophyHypertonia (spasticity or rigidity)Spastic cerebral palsyCalf muscleChildhood-onsetaccumulation of hydroxyproline (aminoacid exclusive to collagen) in calf musclesStiff-person syndromeTorso/limbsAdult-onsetMuscle hypertrophy and EMG demonstrates co-contraction of agonist and antagonist muscles and/or continuous motor unit activity in affected muscles.Denervation (pseudo)hypertrophyPeripheral nerve traumatic injuryCalf muscleVariableDisorders of the anterior horn cells (such as poliomyelitis, spinal muscular atrophy, and Charcot–Marie–Tooth disease)Calf muscleVariableRadiculopathy