Skeletal Muscle Disease Flashcards
- What is this skeletal muscle disease caused by denervation of muscle fiber
- Nerve disease (neuropathy)
- Traumatic nerve injury
- Disease of the nerve paired with muscle fiber
- Affects type 1 and type 2 fibers
- Fiber type grouping seen after renervation
Neurogenic Atrophy
Identify this skeletal muscle disease:
- Common
- caused by immobilization or steroids
- Involves only type 2 fibers (fast twitch)
- Special studies required to distinguish from denervation
- Type 2 myofiberatrophy
What is this skeletal muscle disease?
- Autoimmune disorder involving neuromuscular junction
- Autoantibodies against acetylcholine receptor (demonstrable in 90% of patients)
- Strongly associated with thymoma
- 15-20% of patients
- No morphologic changes
- Idiopathic
- Progressive disease–muscle weakness and fatigue
- Most common muscles affected–eyelids, extraocular muscles
- droopy eyelids (ptosis); double vision
- May affect respiratory muscles if untreated
- Treatment
- Anticholinesterase drugs
- Thymectomy
Myasthenia Gravis
What is this type of muscular dystrophy?
- One of the most severe types
- X-linked inheritance–1 in 3500 male births
- Progressive muscle weakness, starting at pelvis and shoulder
- Starts in early childhood; death in young adulthood from respiratory failure is common
- Molecular: absence of dystrophin (skeletal muscle protein)
- Gene for dystrophin is on X chromosome
Duchenne Muscular Dystrophy
What type of muscular dystrophy?
- Less common and less severe
- Molecular defect: structurally abnormal dystrophin
- We still have dystrophin but maybe just decreased
- Special staining for dystrophin distinguishes the two forms
- Later onset of problems–>adolescent to early adulthood
Becker Muscular Dystrophy
What type of soft tissue tumor has these characteristics: benign, borderline, or malignant?
– Slowgrowing, limited
– Cured with simple excision
Benign
What type of soft tissue tumor has these characteristics: benign, borderline, or malignant?
– Locally aggressive, infiltrating lesions
– Often recur after simple excision; wide excision necessary
–Very rarely metastasize
Borderline
What type of soft tissue tumor has these characteristics: benign, borderline, or malignant?
– Rapid growing, often metastasize
– Lungs most common site of metastasis
Malignant
What type of soft tissue tumor is this?
- adipose tissue
- benign
- Most common soft tissue tumor
- Usually in subcutaneous tissue of adults
- Histologically normal adipose (fat) tissue
Lipoma
What type of soft tissue tumor is this?
- either borderline or malignant
- adipose tissue
- Viscera or deep extremity soft tissues
- Biologic behavior depends on histologic types:
- Well-differentiated and myxoid
- slow growing, local
- Borderline adipose tumor
- Round cell and pleomorphic
- capable of metastasis
- Malignant adipose tumor
- Well-differentiated and myxoid
Liposarcoma
What type of soft tissue tumor is this?
- Reactive fibrous proliferation accompanied by inflammation
- Rapidly growing, but cured by local excision
- May be associated with trauma (10-15%)
- May be mistaken for sarcoma
- “Proliferative lesion”, similar to proliferative myositis
- stops growing at a certain size
- fibrous
- benign behavior
Nodular Fascitis
What type of soft tissue tumor is this?
- Fibrous
- Borderline behavior
Superficial types
- Palmar (Dupuytren’s contracture)
- Plantar
- Penile (Peyronie’s disease)
- fibrous tissue grows and wraps around tendons of hand and they cant be extended
Deep (Desmoid tumor)
- Arise in abdominal wall or viscera
- Locally aggressive tumors, may recur; require wide excision
Fibromatosis
What type of soft tissue tumor is this?
- Fully malignant fibrous tissue tumor
- Grows slowly, but may metastasize to distant structures
- most common is lung
- Viscera or deep extremity soft tissue
Fibrosarcoma
What is this soft tissue tumor?
- fibrohistiocytic
- bengn
- Second most common soft tissue tumor
- Small, sometimes pigmented, mobile skin nodule
- Cured by simple excision
- arise in or right inbetween skin
- firm palpatable bump
Dermatofibroma (Fibrous Histiocytoma)
What is this soft tissue tumor?
- borderline
- fibrohistiocytic
- Fibrohistiocytic tumor of low malignant potential
- Often recur locally; rarely metastasize
- Variably sized, growing nodule; skin and subcutaneous tissue of trunk
- Microscopic–”storiform” pattern
Dermatofibrosarcoma Protuberans
DFSP
