Adult-onset Still disease (AOSD) is a systemic inflammatory condition that clinically manifests as spiking fevers, arthralgia, evanescent skin rash, and lymphadenopathy. 1 The most commonly used criteria for diagnosing AOSD are the Yamaguchi criteria. 2 The major criteria include high fever for more than 1 week, arthralgia for more than 2 weeks, leukocytosis, and an evanescent skin rash. The minor criteria consist of sore throat, lymphadenopathy and/or splenomegaly, liver dysfunction, and negative rheumatoid factor and antinuclear antibodies. Classically, the skin rash is described as an evanescent, salmon-colored erythema involving the extremities. Nevertheless, unusual cutaneous eruptions have been reported in AOSD, including persistent pruritic papules and plaques. 3 Importantly, this atypical rash demonstrates specific histologic findings that are not found on routine histopathology of a typical evanescent rash. We describe 2 patients with this atypical cutaneous eruption along with the unique histopathologic findings of AOSD.
Case Reports
Patient 1
A 23-year-old Chinese woman presented with periodic fevers, persistent rash, and joint pain of 2 years’ duration. Her medical history included splenectomy for hepatosplenomegaly as well as evaluation by hematology for lymphadenopathy; a cervical lymph node biopsy showed lymphoid and follicular hyperplasia.
Twenty days later, the patient was referred to the dermatology department for evaluation of the persistent rash. The patient described a history of flushing of the face, severe joint pain in both arms and legs, aching muscles, and persistent sore throat. The patient did not report any history of drug ingestion. Physical examination revealed a fever (temperature, 39.2°C); swollen nontender lymph nodes in the neck, axillae, and groin; and salmon-colored and hyperpigmented patches and thin plaques over the neck, chest, abdomen, and arms (Figure 1). A splenectomy scar also was noted. Peripheral blood was collected for laboratory analyses, which revealed transaminitis and moderate hyperferritinemia (Table). An autoimmune panel was negative for rheumatoid factor, antinuclear antibodies, and antineutrophil cytoplasmic antibodies. The patient was admitted to the hospital, and a skin biopsy was performed. Histology showed superficial dyskeratotic keratinocytes and sparse perivascular infiltration of neutrophils in the upper dermis (Figure 2).
Figure 1. Clinical presentation of adult-onset Still disease with persistent salmon-colored and hyperpigmented patches over the left hypochondrial region (A) and lower abdomen (B).
Figure 2. Histopathology showed superficial dyskeratotic keratinocytes and equivalent perivascular infiltration of neutrophils in the upper dermis (H&E, original magnification ×10).
The patient was diagnosed with AOSD based on fulfillment of the Yamaguchi criteria.2 She was treated with methylprednisolone 60 mg daily and was discharged 14 days later. At 16-month follow-up, the patient demonstrated complete resolution of symptoms with a maintenance dose of prednisolone (7.5 mg daily).
Patient 2
A 23-year-old black woman presented to the emergency department 3 months postpartum with recurrent high fevers, worsening joint pain, and persistent itchy rash of 2 months’ duration. The patient had no history of travel, autoimmune disease, or sick contacts. She occasionally took aspirin for joint pain. Physical examination revealed a fever (temperature, 39.1°C) along with hyperpigmented patches and thin scaly hyperpigmented papules coalescing into a poorly demarcated V-shaped plaque on the upper back and posterior neck, extending to the chest in a shawl-like distribution (Figure 3). Submental lymphadenopathy was present. The spleen was not palpable.
Figure 3. Clinical presentation of adult-onset Still disease with hyperpigmented patches and thin scaly papules coalescing into plaques over the back in a V-shaped distribution (A) as well as over the chest in a shawl-like distribution (B), mimicking the typical distribution of cutaneous dermatomyositis.
Peripheral blood was collected for laboratory analysis and demonstrated transaminitis and a markedly high ferritin level (Table). An autoimmune panel was negative for rheumatoid factor, antinuclear antibodies, and antineutrophil cytoplasmic antibodies. Skin biopsy was performed and demonstrated many necrotic keratinocytes, singly and in aggregates, distributed from the spinous layer to the stratum corneum. A neutrophilic infiltrate was present in the papillary dermis (Figure 4).
Figure 4. Histopathology showed necrotic keratinocytes, singly and in aggregates, distributed from the spinous layer to the stratum corneum. A neutrophilic infiltrate was present in the papillary dermis (H&E, original magnification ×10).
The patient met the Yamaguchi criteria and was subsequently diagnosed with AOSD. She was treated with intravenous methylprednisolone 20 mg every 8 hours and was discharged 1 week later on oral prednisone 60 mg daily to be tapered over a period of months. At 2-week follow-up, the patient continued to experience rash and joint pain; oral methotrexate 10 mg weekly was added to her regimen, as well as vitamin D, calcium, and folic acid supplementation. At the next 2-week follow-up the patient noted improvement in the rash as well as the joint pain, but both still persisted. Prednisone was decreased to 50 mg daily and methotrexate was increased to 15 mg weekly. The patient continued to show improvement over the subsequent 3 months, during which prednisone was tapered to 10 mg daily and methotrexate was increased to 20 mg weekly. The patient showed resolution of symptoms at 3-month follow-up on this regimen, with plans to continue the prednisone taper and maintain methotrexate dosing.