Dermatomyositis (DM) is a rare autoimmune inflammatory disease where the immune system mistakenly attacks the body’s own tissues, primarily affecting the muscles and the skin. Concerns often extend beyond the commonly discussed symptoms to include cosmetic changes, such as hair loss. Since DM affects skin across the body, the scalp is not exempt from the resulting inflammation. Clarifying the connection between DM disease activity, its treatments, and changes to hair health is important for managing expectations and seeking appropriate care.
Understanding Dermatomyositis
Dermatomyositis is classified as an inflammatory myopathy, characterized by chronic muscle inflammation and weakness. The hallmark symptom is proximal muscle weakness, affecting muscles closest to the torso, such as the hips, thighs, shoulders, and upper arms. This weakness typically develops gradually, making everyday tasks like standing, climbing stairs, or lifting objects difficult.
The presence of specific skin rashes distinguishes dermatomyositis from other inflammatory muscle diseases. These skin manifestations frequently appear before or at the same time as the muscle weakness. One sign is the heliotrope rash, a violaceous or purplish discoloration that appears symmetrically on the upper eyelids, often accompanied by swelling.
Gottron’s papules are another common finding, appearing as reddish or purple, scaly eruptions over the bony prominences of the joints (knuckles, elbows, and knees). Broad areas of photosensitive redness, known as the shawl sign and V-sign, also affect the upper back and neck, or the chest. These rashes demonstrate the systemic nature of the inflammation, indicating the scalp is also vulnerable.
The Direct Link Between Dermatomyositis and Hair Changes
DM disease activity can directly cause hair loss, often signaling uncontrolled systemic inflammation. The scalp is a frequent site of involvement in dermatomyositis, reported in up to 77% of patients. The resulting hair loss, known as alopecia, is typically diffuse and non-scarring, meaning hair follicles are not permanently destroyed and regrowth is possible once the disease is managed.
The inflammatory process directly targets the skin and underlying hair follicles of the scalp. This leads to scalp dermatomyositis, which presents with a combination of symptoms. These findings include erythema (redness), scaling, and pruritus (intense itching) that can sometimes be mistaken for common conditions like psoriasis or seborrheic dermatitis.
A specific feature of scalp involvement is poikiloderma. Poikiloderma is a skin change characterized by hyperpigmentation (darkening), hypopigmentation (lightening), atrophy (thinning), and telangiectasias (dilated blood vessels). When this affects the scalp, chronic inflammation disrupts the hair growth cycle, leading to non-scarring hair thinning.
In patients with active DM, this scalp inflammation causes widespread shedding of hair. The presence of active, scaly, and erythematous patches on the scalp, especially with hair thinning, strongly indicates active disease requiring systemic control. Addressing the underlying inflammation is the primary mechanism for stabilizing the scalp condition and promoting hair recovery.
Distinguishing Hair Loss Caused by Disease Activity Versus Treatment
Pinpointing the cause of hair loss in DM is complex, as both the disease and necessary medications can trigger shedding. Disease-related hair loss is tied to the inflammatory process attacking hair follicles, often presenting with a distinct rash and poikiloderma on the scalp. Conversely, treatment-induced hair loss is a side effect of systemic medications used to suppress the immune system and control DM.
Many immunosuppressive drugs used to treat DM can cause temporary, widespread shedding known as telogen effluvium. This common drug-induced mechanism causes growing hairs to prematurely enter the resting phase and fall out two to four months later. For example, Hydroxychloroquine, a common DM treatment, can cause this type of shedding.
Methotrexate, a frequently prescribed immunosuppressant, is a known culprit for hair thinning. It interferes with the rapid cell division of hair follicles and can deplete folate stores necessary for healthy hair growth. Azathioprine can cause an acute and rapid form of shedding called anagen effluvium, which interferes with the mitotic activity of the growing hair shaft. Differentiating the cause is important for adjusting the therapeutic plan.
Managing Dermatomyositis-Related Scalp and Hair Symptoms
Effective management requires a dual approach addressing both systemic disease and localized skin symptoms. Since hair loss is driven by autoimmune inflammation, the first step is achieving control over systemic disease activity. This requires systemic immunosuppressive medications, which are necessary to stop the immune attack on the body, including the scalp, despite potential side effects.
Localized treatment manages specific symptoms of scalp dermatomyositis, such as redness, scaling, and itching. High-potency topical corticosteroids are often prescribed to reduce inflammation and suppress the localized immune response. Topical calcineurin inhibitors, such as tacrolimus, provide an alternative option to manage inflammation without the risks associated with long-term steroid use.
Rigorous sun protection is an important component of care, as ultraviolet (UV) light exposure can trigger and exacerbate DM skin symptoms on the scalp. Patients should employ sun-protective measures, such as wearing wide-brimmed hats and using broad-spectrum sunscreens formulated for the scalp. Gentle hair care practices, including mild, non-irritating shampoos, are also recommended to minimize trauma to vulnerable hair follicles.