Dermatomyositis - Nail and Distal Digit
See also in: Overview,Cellulitis DDx,External and Internal EyeAlerts and Notices
Synopsis
The distinctive nail findings of dermatomyositis help distinguish it from other connective tissue disorders. Thickened, hyperkeratotic, ragged cuticles and telangiectasias of the proximal nail fold (PNF) are the characteristic nail findings. Some other rare nail findings have been reported, including complete loss of several toenails, red lunulae, and ventral pterygium. The presence of ischemic lesions might be predictive of malignancy in dermatomyositis of adulthood.
In addition to the nail findings, other cutaneous findings such as periorbital heliotrope rash, atrophic dermal papules of dermatomyositis (ADPDM, formerly called Gottron papules) (slightly atrophic, flat-topped papules over the proximal interphalangeal joints), and poikiloderma should also be present. ADPDM may involve the vicinity of the PNF. Other characteristic features may include flat erythema of the upper back and posterior neck and shoulders (shawl sign) as well as a similarly presenting macular erythema of the anterior neck and upper chest (V sign) that can worsen with ultraviolet exposure. Patients may also have poikiloderma over the lateral hip (holster sign). Muscle involvement affects proximal muscle groups in a symmetric fashion.
Dermatomyositis may be induced by medications, including hydroxyurea, penicillamine, interferon beta, and ipilimumab. Acute onset / flares of dermatomyositis have been reported in association with ingestion of IsaLean, an herbal supplement.
Codes
ICD10CM:M33.10 – Other dermatomyositis, organ involvement unspecified
SNOMEDCT:
396230008 – Dermatomyositis
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Diagnostic Pearls
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Differential Diagnosis & Pitfalls
- SLE – Violaceous color and extensor-limited skin disease not seen in lupus erythematosus (LE). Digital macules and thin plaques typically do not involve the knuckles but rather are seen on interdigital skin. Pruritus is not so prominent in LE. Check anti-double stranded DNA, anti-Smith if considering LE.
- Phototoxic / photoallergic drug eruptions
- CREST syndrome – Can have overlap with dermatomyositis. Refers to a subset of patients with limited scleroderma.
- Scleroderma – Check for anticentromere antibodies and anti-Scl-70 antibodies. Typified by sclerotic changes in the skin not seen in dermatomyositis.
- Graft-versus-host disease – Occurs after allogeneic stem-cell transplantation.
- Mixed connective tissue disease – Check for anti-U1 ribonucleoprotein (RNP) antibody. Most patients are positive for this in mixed connective tissue disease.
- Raynaud phenomenon – No systemic involvement.
- Polymyositis – Without cutaneous findings.
- Acute lesions of erythropoietic protoporphyria may have similar locations, especially on the dorsum of the hands, but usually there is no weakness.
- Psoriasis
- Irritant dermatitis
- Atopic dermatitis
- Contact dermatitis
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Management Pearls
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Therapy
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Drug Reaction Data
Below is a list of drugs with literature evidence indicating an adverse association with this diagnosis. The list is continually updated through ongoing research and new medication approvals. Click on Citations to sort by number of citations or click on Medication to sort the medications alphabetically.Subscription Required
References
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Last Reviewed:07/25/2019
Last Updated:12/21/2021
Last Updated:12/21/2021
Patient Information for Dermatomyositis - Nail and Distal Digit
Overview
Dermatomyositis is an inflammatory disease that causes muscle weakness and skin rashes.Who’s At Risk
Dermatomyositis is a rare disease that is more common in women than in men. Adults most often develop dermatomyositis between the ages of 45 and 60. There is also a childhood form of the disease called juvenile dermatomyositis.Signs & Symptoms
A violet rash develops, most commonly on your face and eyelids. The rash can also appear on your knuckles, chest, knees, nails, and back. The purple, patchy rash is often the first sign of dermatomyositis.Dermatomyositis also causes muscle weakness that tends to start in the trunk area, such as your hips, shoulders, neck, upper arms, and thighs. The weakness tends to get gradually worse.
Self-Care Guidelines
The rash is sensitive to the sun. Avoid too much exposure to the sun and wear protective clothing and SPF 45 or higher sunscreen.For support groups, see the Myositis Association website at http://www.myositis.org/your-myositis-community/support-groups.
When to Seek Medical Care
There is no cure for dermatomyositis. However, the sooner treatment is started, the better the results. It is important to keep in touch with your doctors during treatment.Treatments
Corticosteroids (prednisone) are effective in controlling dermatomyositis symptoms. However, they have side effects after prolonged use. Corticosteroid-sparing agents can be used to reduce the dosage and side effects of corticosteroids.If the rash is severe, antimalarial medication can be administered.
Physical and speech therapy can help you improve your muscle strength.
Depending on your symptoms, there may be other options you will want to discuss with your health care provider. Your doctors will tailor individual treatment to you.
Dermatomyositis - Nail and Distal Digit
See also in: Overview,Cellulitis DDx,External and Internal Eye