Ovoid palatal patch: a clue to anti-TIF1γ dermatomyositis

Abstract

An 80-year-old woman presented with a several-year history of progressive hair loss and scalp pruritus. No other rashes or muscle weakness were noted on examination. Scalp biopsy showed interface dermatitis, dense perivascular and periadnexal lymphocytic infiltrate, mucin and scarring alopecia. Laboratory analysis did not show evidence of myositis. The patient was started on hydroxychloroquine for possible cutaneous lupus erythematosus. On follow-up, she presented with a new violaceous rash on the superior eyelids and a well-defined oval patch on the mid-hard palate suspicious for dermatomyositis. Myositis-specific autoantibodies revealed presence of anti-transcriptional intermediary factor-1γ (anti-TIF1γ) in the serum. Anti-TIF1γ autoantibody-positive dermatomyositis is a newly recognised subtype of dermatomyositis that is highly associated with amyopathic disease and has an increased risk of malignancy, making prompt diagnosis crucial. This case highlights the utility of a thorough oral exam in patients suspected to have connective tissue disease as the distinctive ovoid palatal patch is nearly pathognomonic for anti-TIF1γ dermatomyositis.

Background

Dermatomyositis is a multisystem autoimmune disease that often involves inflammation of the skin and muscles. Several cutaneous manifestations, such as the shawl sign, Gottron papules and heliotrope rash, are highly characteristic of dermatomyositis while others are less specific and range from diffuse hair loss to mucosal lesions. Whether pathognomonic or non-specific, cutaneous manifestations are important features of the disease and their correct evaluation enables early detection and diagnosis. This report describes the management of a woman with amyopathic dermatomyositis whose diagnosis was aided by a little recognised and possibly pathognomonic finding on oral examination.

Recently, dermatomyositis has been categorised into several newer subtypes based on the association with specific autoantibodies including anti-Mi-2, anti-transcriptional intermediary factor-1γ (anti-TIF1γ) and antimelanoma differentiation-associated gene 5 (anti-MDA5). Further characterisation of the anti-TIF1γ antibody subtype has revealed distinct clinical features, including an increased association with underlying malignancy and amyopathic dermatomyositis. As such, patients lack the classic muscle findings of dermatomyositis, making the diagnosis of this disease subtype challenging. However, early diagnosis is crucial as it facilitates prompt cancer screenings and has the potential to decrease morbidity and mortality in these patients. The clinical finding described in this case has only recently been reported and may offer a vital clue in the early diagnosis of patients with anti-TIF1γ antibody-positive dermatomyositis.

Case presentation

An 80-year-old Hispanic woman with a history of hypertension, hyperlipidemia and diabetes mellitus presented with a several-year history of scalp pruritus and hair loss. At the time of presentation, she was noted to have diffuse patchy alopecia, in some areas with loss of follicular ostia, on a background of diffuse mild erythema, fine scale and reticulate hyperpigmentation (figure 1). She did not have rash elsewhere and denied any muscle weakness.

Figure 1.

Diffuse, patchy alopecia of the vertex scalp with reticulate hyperpigmentation and erythema.

Biopsy of the scalp showed interface dermatitis, a dense perivascular and periadnexal lymphocytic infiltrate with increased dermal mucin and scarring alopecia. Discoid lupus erythematosus and dermatomyositis were both considered in the differential. The patient was evaluated by rheumatology and workup revealed normal serum levels of aldolase and creatine kinase, as well as a negative antinuclear antibody (ANA). Given low clinical suspicion for dermatomyositis and lack of symptoms or signs suggestive of muscle weakness rheumatology did not feel that additional testing, including muscle biopsy or MRI, were warranted. At that time, a diagnosis of discoid lupus erythematosus was favoured. She was started on hydroxychloroquine 200 mg twice daily, which she took for a few months with no significant relief before discontinuing due to loss of appetite.

She was briefly lost to follow-up and then re-presented with persistent scalp pruritus, mild swelling of the superior eyelids and an ill-defined hyperpigmented and minimally scaly patch on the upper back (figure 2). Although the new skin findings were suspicious, they were not completely consistent with typical heliotropic rash or shawl sign. Interestingly, the oral examination revealed a well-demarcated, erythematous oval patch on the mid-hard palate, raising suspicion for a specific subtype of dermatomyositis associated with anti-TIF1γ autoantibodies (figure 3). Biopsy of this patch demonstrated subtle interface inflammation and subtle vacuolar changes. Subsequent testing of 11 myositis-specific autoantibody panel confirmed the presence of anti-TIF1γ antibody in patient’s serum. The patient was treated with fluocinolone oil as needed for scalp pruritus and also started on oral methotrexate, initially at 10 mg weekly, which was titrated up to 17.5 mg weekly over the course of 8 weeks. The patient was strongly recommended to undergo age-appropriate cancer screening, transvaginal ultrasound, total colonoscopy and CT of lung, abdomen and pelvis but she declined.

Figure 2.

Ill-defined, hyperpigmented mildly scaly brown patch on the upper back.

Figure 3.

Smooth, well-demarcated erythematous and hyperpigmented oval patch on the mid-hard palate.

Outcome and follow-up

At a 5-month follow-up, the patient reported dramatic improvement in her scalp pruritus and erythema on methotrexate. She had no evidence of the previously noted eyelid swelling and the rash on her back had completely resolved. She continued to deny muscle weakness and her review of systems remained negative. ANA testing was repeated and was negative. Efforts were made to encourage appropriate cancer screenings; however, the patient declined. She has not developed any evidence of malignancy since the start of her dermatomyositis more than 4 years ago, making the possibility of underlying cancer unlikely.

Discussion

The ovoid palatal patch, a rare and recently described entity, presents as an asymptomatic symmetric, smooth and arcuate patch across the mid-hard palate. Few reported case reports and a small cohort study suggest that the ovoid palatal patch may be a specific finding for anti-TIF1γ positive adult-onset dermatomyositis; however, larger studies are needed to validate this observation.^{1 2} The largest cohort study that has been done to date reported presence of the ovoid palatal patch in 18 out of 45 patients with adult-onset dermatomyositis (40%).² Interestingly, 100% of the cases with this clinical finding had anti-TIF1γ in their serum.²

Anti-TIF1γ antibodies are also present in a higher percentage of patients with amyopathic dermatomyositis, as seen in our patient.^{3 4} Clinically diagnosing amyopathic dermatomyositis can be challenging as the correct diagnosis relies primarily on identification of characteristic skin findings. Unfortunately, in many cases these findings might be minimal and easily overlooked. Performing a thorough oral exam and identifying the ovoid palatal patch may offer important diagnostic evidence when faced with a patient in whom one suspects connective tissue disease.

In the case described above, a diagnosis of cutaneous lupus was initially favoured over dermatomyositis because the patient did not have any symptoms, signs, clinical or laboratory findings suggestive of dermatomyositis. Biopsy of the patient’s scalp was not helpful in informing the diagnosis because the histological features of cutaneous lupus and dermatomyositis are almost identical. ANA was negative on initial testing and at follow-up, further obscuring the diagnosis. It is worth noting that ANA may be negative in up to 39% of cases with adult-onset dermatomyositis.⁵ Identifying the ovoid-palatal patch at follow-up made us suspicious for dermatomyositis, and detecting positive anti-TIF1γ in the patient’s serum confirmed the diagnosis. Although we cannot be certain that the patient had the ovoid palatal patch at initial presentation, examining her oral cavity could potentially have led to the correct diagnosis at an earlier stage.

Dermatomyositis with anti-TIF1γ antibodies portends a higher risk of underlying malignancy and as such should prompt the clinician to initiate cancer screening.⁶ Specifically, this form of dermatomyositis has been associated with increased risk of thyroid, pancreas and ovarian cancers.^{1 3} Preliminary data suggest that patients with adult-onset dermatomyositis associated with an underlying malignancy tend to have cancers at higher stages in the presence of anti-TIF1γ antibodies, further highlighting the importance of early diagnosis and malignancy workup.⁶

There is currently no consensus among clinicians on the extent and frequency of cancer screening in patients with adult-onset dermatomyositis. However, a thorough history and physical examination, age-appropriate cancer screening and transvaginal ultrasound in female patients seem to be the minimum measures indicated.

Learning points.

• The histological features of cutaneous lupus erythematosus and dermatomyositis are almost identical, making skin biopsy unhelpful in informing the diagnosis.

• The ovoid palatal patch offers a unique diagnostic clue in patients with antitranscriptional intermediary factor-1γ (anti-TIF1γ) autoantibody positive dermatomyositis.

• This subtype of dermatomyositis is important to distinguish from other subtypes as it may portend a higher risk of underlying malignancy.

• Anti-TIF1γ autoantibody positive dermatomyositis is highly associated with amyopathic dermatomyositis.