Ch. 42-Dermatomyositis Flashcards
Difference in pathophysiology of polymyositis vs. dermatomyositis?
Polymyositis-Autoreactive CD8+ T-cells clonal expansion, attack myocytes with MHC class I antigens
DM-Activation humoral immune response with complement deposition
What % DM patients have malignancy?
25%
What are the idiopathic inflammatory myopathies?
DM
PM (antisynthetase syndrome included)
Inclusion body
Necrotizing autoimmune myopathy
Overlap
What % DM patients amyopathic?
20%
What are the clinical subtypes DM
Adult onset classic (classic, with malig, with CTD)
Adult onset amyopathic
Adult onset hypomyopathic /(no sx but lab/image evidence)
Drug induced
Juvenile onset with above classifications
Juvenile Onset:
Classical DM.
Clinically Amyopathic DM:
· Amyopathic.
· Hypomyopathic.
Drug-induced
Most common DM ASSOCIATED antibodies
anti-Ro52 (SSA)
anti-PM-Scl
anti-Ku
anti-U1RNP.
Age of onset DM?
Bimodal: Age 7-10 and age 50
Name the 6 DM specific antibodies
anti-aminoacyl-tRNA synthetases (Jo-1, PL-7, PL-12) –> Anti synthethase syndrome
anti-Mi-2 DM
anti-MDA5 DM
anti-TIF1 DM(P155/p140)
anti-NXP2 DM
anti-SAE DM
Also anti-SRP-necrotizing myopathy in blacks, severe disease, no skin
What is anti-synthetase syndrome?
Myositis
Fever
Mechanics hands
ILD
Raynauds
Erosive poly arthritis
Anti-SRP associated DM
Acute-onset necrotizing myopathy (severe weakness, high CK)
may be refractory to treatment
Cardiac involvement
Anti-Mi-2 DM
Classic adult and juvenile DM
-high creatine kinase levels
- good response to treatment
- good prognosis, although relapses often occur.
-ILD is rare in anti-Mi-2 DM
-No malig
What 2 ab-associated DM’s are amyopathic/hypomyopathic?
Tiff-1-gamma
MDA5
Features of Tiff-1-gamma DM?
Mild myositis
Highly malignancy associated in adults
Extensive cutaneous rash:
-with blistering and erosions, psoriasiform lesions on palms, ovoid palatal patch, red on white telangiectatic patches, palmar hyperkeratotic papules (inverse gotttrons)
Vasculopathy
Dysphagia can be severe
Features of MDA5 DM
Amyopathic/hypo
High risk rapidly progressive ILD (in East Asian especially but also not was asian)
Skin-
-Ulcerations over gottrons papules, elbows,
-mucosal ulcerations
-tender palmar papules
-alopecia
Vasculopathy
Arthritis
Clinical features NXP-2
Prominent myositis with mild skin, even absent in some patients (DM sine dermatitis)
2nd high risk malignancy
Calcinosis and peripheral oedema is also characteristic, dysphagia
Common in kids but no malignancy risk
Clinical features SAE
may present with clinically amyopathic DM
Extensive rash
Dysphagia
mild ILD
Malignancy associated
Psoriasiform reaction to plaquenil
Name the classic cutaneous signs of DM?
Heliotrope rash
Poikolderma in V-neck or shawl sign or Holster sign, facial erythema
Gottrons papules
Gottrons sign
Raynauds
Nailfold changes (dilated and drop out capillaries)
Calcinosis cutis
Psoriasiform lesions
scalp poikiloderma,scalingand non scarring alopecia
Describe heliotrope rash of DM
pink–violet color of the eyelids and periorbital skin, +- edema
Can be only mild erythema, may wax and wane in intensity.
May have more widespread facial erythema or midfacial erythema that tends to involve the nasolabial folds (vs. lupus)
What are the nail fold changes in DM?
Cuticular dystrohphy: Ragged cuticles and cuticular hypertrophy
Dilated capillaries alternating with capillary drop out
What is Gottron sign vs. papules
Gottron’s papules: lichenoid papules on the knuckles
Gottron’s sign: thin plaques, papules and pink-violet erythema over elbows or knees (often in addition to knuckles)
What is the v-sign, shawl sign and holster sign?
Poikoldermatous photo distributed eruption of neck (V-sign), shoulders/back (shawl) and lateral thigh (holster)
In lupus more red, DM more violet-pink (unless darker skin then maybe red)
Sometimes there is white silvery scale
What is the one symptom of the rash in DM to help distinguish from LE?
Pruritus!
Is calcinosis more common in adults or juvenile DM
Juvenile 25-75%
Where does calcinosis occur in DM?
Favor sites of trauma (elbows, knees) but can occur anywhere
Often painful, hard, irregular papules or nodules that can sometimes drain chalky material
Can also occur in fascia and intramuscular connective tissues
Name some less common findings in DM
Cutaneous erosions or ulcerations
Flagellate erythema
Tender palmar papules
Hyperkeratotic palmar papules
Exfoliative erythroderma
Cutaneous eruption that mimics PRP (Wong variant in asians)
Vesiculobullous lesions
Pustular eruption of the elbows and knees
Ovoid palatal patch
Gingival telangiectasias
Panniculitis
Lipoatrophy (especially in juvenile dermatomyositis)
Small vessel vasculitis (especially in juvenile dermatomyositis)
Scalp pruritic plaques and alopecia
psoarisiform palmar papules
Which muscles most affected in dM
Proximal >Distal
Especially extensors (triceps and quads)
Which muscles most affected in dM
Proximal >Distal
Especially extensors (triceps and quads)
How does the lung disease present in DM
Diffuse interstitial fibrosis
Dry cough and dyspnea
How to screen for ILD in DM?
PFTs with DLCO
If DLCO impaired–> high rest CT
What % patients have ILD?
15-30%
What DM-specific ab most associated with rapidly progressive ILD?
MDA-5:
-in Eastern Asian populations with anti-MDA5
-non-Asian population with tender palmar papules and cutaneous ulcerations, primarily on the elbows, dorsal hands, and periungual region
Anti-synthethase syndrome (PL7, Jo-1)
% chance pulmonary disease if Jo-1 +
70% chance ILD
Other than malignancy, what is major contributor to death in DM?
Cardiac involvement which is often asymptomatic, often dsyrhytmias or conduction defects
Most common overlaps CTD with DM?
RA
Scleroderma
Systemic LE
Other than skin and muscle, other organs affected in DM?
GI-dysphagia
Cardiac-conduction defects
Joints/arthritis
Rayanuds
Malignancy screening
Risk of malignancy in DM
15-25%
*For classic and amyopathic
Not juvenile or polymyositis
At which point after no malignancy found are you at normal baseline risk?
3 yrs
Most common malignancies in DM?
GU-ovarian esp.
Colorectal
Nasopharyngeal in asian
Other common ones:
Breast
Lung
gastric
pancreatic
Lymphoma
2 antibodies with highest association with malignancy
Tiff-1 gamma
NXP2
Workup for suspected DM?
Skin: biopsy
Labs: CBC, LEs, Cr,Mitogen panel for Ab’s/ANA
Muscles: CK, AST/ALT, muscle MRI vs. EMG and muscle biopsy (increasingly more MRI’s being done)
Lungs: PFTs +- high res CT
Cardiac: EKG
If dysphagia: manometry
Malignancy workup for DM
History and physical!
UA
FOBT
Pelvic US
Pap smear
Mammogram
CT CAP
Labs:
CBC, PSA, CA 19-9, CA 125 (women)
Colonoscopy–> if age-appropriate, iron deficiency anemia, occult blood in stool, or symptoms
EGD–> If IDA, symptoms, occult blood
*annually for 3 years
*Can add SPEP
Histopath findings in DM
Epidermis
-epidermal atrophy
-interface dermatitis with vacuolar alteration of basal keratinocytes
-pigment incontinence
-Gottron papules show an interface dermatitis but have acanthosis and hyperkeratosis rather than epidermal atrophy
dermal changes
- mucin deposition
- sparse lymphocytic infiltrate.
- may be indistinguishable from those of LE. G
muscle biopsy findings
type II muscle fiber atrophy, necrosis, regeneration, and hypertrophy with centralized sarcolemmal nuclei, plus lymphocytes in both a perifascicular and a perivascular distribution, is classic
What muscle to biopsy in suspected myositis
triceps
Best therapeutic option for DM with clinically significant myosititis
Oral prednisone:
1 mg/kg/day tapered to 50% over 6 months and to zero over 2–3 years
True or false: Treatment response of muscles and skin are similarly aligned and follow same trajectory
FALSE-very discordant
Treatment ladder for myositis aspect
Lifestyle: Physical therapy
Prednisone
Often add steroid-sparing:
e.g. MTX. AZA, MMF etc.
Ritux and IVIG also evaluated, not much effect on skin it seems but ritux was helpful
Treatment of amyopathic DM
Evidence weak, often hard to treat, and sometimes myositis improves but cutaneous doesn’t
-topical corticosteroids
-topical tacrolimus
-antimalarial therapy (either as monotherapy or in combination, which is less dramatic in its effect than when used for cutaneous LE and an increased risk of a cutaneous drug reaction to hydroxychloroquine
-low-dose weekly methotrexate,
-mycophenolate mofetil
-IVIg
-dapsone
-tofacitinib
-thalidomide
Common treatment ladder for cutaneous DM/amyopathic
Anti-malarials, then MTX, then MMF
then IVIg for cases of refractory cutaneous dermatomyositi
Treatment calcinosis
Amlodipine
surgical excision
Others:
low-dose warfarin, bisphosphonates, probenecid, colchicine, TNF inhibitors, aluminum hydroxide, sodium thiosulfate, and electric shock wave lithotripsy (ESWL).
