Ch. 42-Dermatomyositis Flashcards by Hannah Stirton

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

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What % DM patients have malignancy?

25%

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What are the idiopathic inflammatory myopathies?

PM (antisynthetase syndrome included)

Inclusion body

Necrotizing autoimmune myopathy

Overlap

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What % DM patients amyopathic?

20%

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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

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Most common DM ASSOCIATED antibodies

anti-Ro52 (SSA)
anti-PM-Scl
anti-Ku
anti-U1RNP.

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Age of onset DM?

Bimodal: Age 7-10 and age 50

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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

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What is anti-synthetase syndrome?

Myositis
Fever
Mechanics hands
ILD
Raynauds
Erosive poly arthritis

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Anti-SRP associated DM

Acute-onset necrotizing myopathy (severe weakness, high CK)
may be refractory to treatment
Cardiac involvement

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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

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What 2 ab-associated DM’s are amyopathic/hypomyopathic?

Tiff-1-gamma
MDA5

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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

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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

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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

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Clinical features SAE

may present with clinically amyopathic DM

Extensive rash

Dysphagia

mild ILD

Malignancy associated

Psoriasiform reaction to plaquenil

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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

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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)

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What are the nail fold changes in DM?

Cuticular dystrohphy: Ragged cuticles and cuticular hypertrophy

Dilated capillaries alternating with capillary drop out

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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)

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What is the v-sign, shawl sign and holster sign?

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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?

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Pruritus!

Is calcinosis more common in adults or juvenile DM

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Juvenile 25-75%

Where does calcinosis occur in DM?

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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).

Ch. 42-Dermatomyositis Flashcards

(50 cards)