MS - Path (Polymyositis/dermatomyositis, Neuromuscular junction diseases, & Myositis ossificans)

Question 1

What defines and characterizes polymyositis?

Answer 1

Polymyositis - progressive symmetric proximal muscle weakness, characterized by endomysial inflammation with CD8+ T cells

Question 2

What part of the body does polymyositis most often involve?

Answer 2

Most often involves shoulders

Question 3

Compare/Contrast dermatomyositis to polymyositis. Include 5 specific signs/symptoms of dermatomyositis.

Answer 3

Dermatomyositis - similar to polymyositis, but also involves (1) malar rash (similar to SLE), (2) Gottron papules, (3) heliotrope (erythematous periorbital) rash, (4) “shawl and face” rash, (5) “mechanic’s hands.”

Question 4

What kind of rash is seen in dermatomyositis? What other condition has a similar rash?

Answer 4

Malar rash (similar to SLE)

Question 5

What risk does dermatomyositis increase?

Answer 5

Increase risk of occult malignancy

Question 6

What occurs to the perimysium in dermatomyositis?

Answer 6

Perimysial inflammation and atrophy with CD4+ T cells

Question 7

What are 5 lab findings associated with polymyositis/dermatomyositis?

Answer 7

(1) High CK (2) + ANA (3) + anti-Jo-1 (4) + anti-SRP (5) + anti-Mi-2 antibodies

Question 8

Compare/Contrast Myasthenia gravis and Lambert-Eaton myasthenic syndrome in terms of frequency.

Answer 8

MYASTHENIA GRAVIS - Most common NMJ disorder; LAMBERT-EATON MYASTHENIC SYNDROME: Uncommon

Question 9

Compare/Contrast Myasthenia gravis and Lambert-Eaton myasthenic syndrome in terms of pathophysiology.

Answer 9

MYASTHENIA GRAVIS - Autoantibodies to postsynaptic ACh receptor; LAMBERT-EATON MYASTHENIC SYNDROME: Autoantibodies to presynaptic Ca2+ channel => low ACh release

Question 10

Compare/Contrast Myasthenia gravis and Lambert-Eaton myasthenic syndrome in terms of clinical symptoms.

Answer 10

MYASTHENIA GRAVIS - Ptosis, diplopia, weakness, Worsens with muscle use; LAMBERT-EATON MYASTHENIC SYNDROME: Proximal muscle weakness, autonomic symptoms (dry mouth, impotence), Improves with muscle use

Question 11

What are 2 malignant conditions with which myasthenia gravis is associated?

Answer 11

Thymoma, Thymic hyperplasia

Question 12

What is the malignant condition with which Lambert-Eaton myasthenic syndrome is associated?

Answer 12

Small cell lung cancer

Question 13

Compare/Contrast Myasthenia gravis and Lambert-Eaton myasthenic syndrome in terms of AChE inhibitor administration.

Answer 13

MYASTHENIA GRAVIS - Reversal of symptoms; LAMBERT-EATON MYASTHENIC SYNDROME: Minimal effect

Question 14

What is myositis ossificans, and in what context does it occur?

Answer 14

Metaplasia of skeletal muscle to bone following muscular trauma

Question 15

In what body part(s) is myositis ossificans most often seen?

Answer 15

Most often seen in upper or lower extremity

Question 16

What are 2 ways in which myositis ossificans may present?

Answer 16

May present as (1) suspicious “mass” at site of known trauma or as (2) incidental finding on radiography

Question 17

Again, what are 3 symptoms of myasthenia gravis? Do they improve or worsen with muscle use?

Answer 17

Ptosis, diplopia, weakness; Worsens with muscle use

Question 18

Again, what are 3 symptoms of Lambert-Eaton myasthenic syndrome? Do they improve or worsen with muscle use?

Answer 18

Proximal muscle weakness, autonomic symptoms (dry mouth, impotence); Improves with muscle use