MSK Dx

Question 1

{{BLANK}} myopathy is assoc. w/ serum CK elevations and rhabdomyolysis

Answer 1

Hypothyroid

Question 2

{{BLANK}} myopathy is assoc. w/ myofiber necrosis & regeneration

Histologic findings

Answer 2

Thyrotoxic myopathy

Question 3

{{BLANK}} is a potent vasoconstrictor that can lead to diffuse ischemia & rhabdomyolysis

Direct effects on myocytes –> Rhabdomyolysis

Answer 3

Cocaine

Question 4

Statins can inhibit the synthesis of {{BLANK}} which plays a key role in muscle cell energy production

Answer 4

CoQ10

Question 5

{{BLANK}} is a direct mitochondrial toxin & can cause rhabdomyolysis & ARF secondary to myoglobinuria

Also: Electrolyte abnormalities – phosphate, K, Mg, Ca

Answer 5

EtOH Myopathy

Question 6

What is the Rhabdo triad?

Answer 6

• Myalgia
• Generalized weakness
• tea-colored urine (myoglobin)

Question 7

What is displayed in the histopathology slide attached? What disease does this patient likely have?

Answer 7

• Ragged Red Fibers
• MERRF

Question 8

{{BLANK}} is due to a point mutation in mit-DNA leading to generalized seizures, cerebellar ataxia, and dementia.

Destruction of oxidative phosphorylation proteins

Answer 8

MERRF

Question 9

{{BLANK}} is due to maternally inherited mit-DNA mutations that result in muscle weakness and tonic-clonic seizures

Answer 9

MELAS (encephalomyopathy, lactic acidosis, and stroke-like episodes)

Question 10

{{BLANK}} has the hallmark S/Sx of the inability to relax voluntary muscle after contraction

Answer 10

Myotonic dystrophy

Question 11

Myotonic dystrophy displays {{BLANK}} as the risk increases with progeny

Answer 11

Anticipation; CTG repeats

Question 12

Most myotonic dystrophy cases are due to a defective {{BLANK}} enzyme

Answer 12

DMPK

Question 13

Prefentially, {{BLANK}}-muscle fibers are affected in myotonic dystrophy

Answer 13

Type I (slow-twitch)

Question 14

DMD and BMD both result in deleted dystrophin but {{BLANK}} is worse and more aggressive

Answer 14

DMD

Question 15

Inclusion body myositis is most severe in the muscles: {{BLANK}} and {{BLANK}}

Answer 15

• Quadriceps
• UE muscles

Question 16

A 67 yo man comes in complaining of weakness when lifting his grandchild and their right leg when rising from their desk char. The patient also has been experiences difficulty swallowing their morning meds. Attached is the histopathology sample you gathered from their quadriceps. What do you suspect?

Answer 16

Inclusion body myositis

Asymmetric weakness of UE & quads w/ inclusion bodies

Question 17

C&C polymyositis with dermatomyositis

Answer 17

• Polymyositis: Endomysial; CD8+ T cells; Adults; No skin
• Dermatomyositis: Permysial; CD4+ T cells; children & adults; skin

Tx w corticosteroids & immunosuppressants; both ANA & Anti-Jo1

Question 18

Screen for a paraneoplastic syndrome in which areas if you find dermatomyositis?

Answer 18

SLOB
* Stomach
* Lung
* Ovaries
* Breast

Remember: Skin manifestations (Heliotrope rash, gottron papules)