Atypical Case of Toe-Walking and Hyperpigmented Rash in a 9-year-old Boy

A previously healthy 9-year-old boy presents with 3 months of progressive toe-walking and violaceous hyperpigmentation of the right lower extremity. Initially, he noticed a dark purple discoloration behind his right lateral malleolus associated with heel pain without any preceding injury or trauma to the area. During the next week, the discoloration increased in size, extending from his toes to his ankles, and now with a tight sensation in his lower leg. He was noted to be walking on his toes and was seen by his primary care physician, who referred to physical therapy. During the next 2 months, the discoloration and tightening spread to the lateral aspect of the right foot, calf, and thigh, with sparing of the superior calf to the knee. In the 2 weeks before presentation, he had rapid progression of this skin tightening, spreading up to the posterior thigh and buttock. He denies any other joint pain, fevers, fatigue, night sweats, or weight changes. During this time, his gait progressed to complete toe-walking on the right side. He was referred to orthopedic surgery, and at that visit he was directed to our emergency department given his skin discoloration and examination findings.On examination, his right dorsal foot has a dark violaceous plaque tracking from the third and fourth toes to the right lateral malleolus that is very firm, smooth, and warm to the touch. The plaque extends up the lower segment of his right calf, spares the knee, and resumes along the lateral aspect of his right thigh (Fig 1). The underlying skin is tense, thickened, and indurated, with significant matting and lipodystrophy with a peau d'orange appearance (Fig 2). His right knee is slightly contracted with resistance to passive range of motion, and his right foot is fixed in a 90° angle of plantarflexion. Passive and active range of motion of the second, third, and fourth toes is restricted, and there are no obvious lesions between the toes. There is notable atrophy of the right lower extremity (Fig 2). There is a groove sign with a sunken line at the small saphenous vein (Fig 3). Sensation to light touch is intact throughout the right leg, pulses are 2+ and symmetrical, and capillary refill is normal. The left leg is normal on examination. His gait is abnormal, with his right knee held in flexion and his right ankle in plantarflexion such that he can only walk with his toes down and without heel strike. He has no telangiectasias, trismus, digital capillaritis, or Raynaud phenomenon in any extremity.Initial laboratory evaluation shows an elevated erythrocyte sedimentation rate of 43 mm/hr, peripheral eosinophilia to 1,340/μL (1.34 × 109/L; 19.4%) (reference range, 50–220/μL [0.05–0.22 × 109/L; 2%–4%]), and hypergammaglobulinemia with an IgG level of 1,954 mg/dL (19.54 g/L) and an IgA level of 491.6 mg/dL (4.92 g/L). Laboratory evaluation also reveals negative antinuclear antibody, Lyme IgG and IgM antibodies, antineutrophil cytoplasmic antibody, Smith antibodies, ribonucleoprotein antibodies, and double-stranded DNA antibodies, as well as normal C3 and C4 levels. A magnetic resonance image (MRI) of the right leg was obtained and incidentally showed part of the left leg with abnormal signal enhancement in addition to findings in the right leg. Bilateral MRI was subsequently obtained that is notable for thickening of muscle fascia in the bilateral lower extremities, above and below the knees (Fig 4 and Fig 5). Significant fascial thickening is noted on the right vastus lateralis extending to the posterior rectus femoris, with similar but less pronounced changes on the left. Tissue biopsy confirms the diagnosis.The initial differential diagnosis for this presentation included diffuse scleroderma, linear scleroderma, eosinophilic fasciitis (EF), Borrelia-associated morphea, and paraneoplastic syndrome. A full-thickness biopsy of the right thigh showed extremely thick fascia with sclerosis and inflammation, with sclerotic bands extending through the subcutaneous tissue tethering deep dermis to the fascia. There is a focal increase in eosinophils, confirming the diagnosis of EF (Fig 6).EF is a rare disorder that typically presents with symmetrical swelling and platelike hardness of the distal limbs with painless contractures limiting mobility, eosinophilia, hypergammaglobulinemia, and elevated erythrocyte sedimentation rate. Characteristic physical examination findings in EF include a peau d'orange appearance of the skin and a groove sign in affected extremities. Groove sign occurs because of fascial sclerosis causing immobility of connective tissue surrounding superficial veins, with sparing of the epidermis and dermis. When the affected extremity is elevated, peripheral venous pressure decreases, and the peripheral skin is tethered in with accentuated depression along the course of veins. (1) Eosinophilia is present in 63% to 93% of patients, although the absence of eosinophilia does not exclude disease. (2)The etiology of EF is not well understood. Reported triggers include muscle trauma; drugs such as statins, phenytoin, ramipril, subcutaneous heparin, and trichloroethylene; infections such as Borrelia burgdorferi and Mycoplasma arginini; hematologic disorders; solid neoplasms; and autoimmune disorders. (2) EF occurs very rarely in children. In a retrospective study at the scleroderma clinic at Thomas Jefferson University, 12 patients were identified as having EF during a 10-year period, and the mean age at diagnosis was 49.8 years. (3) Joint contractures were the most common extracutaneous manifestation of EF and were seen in two-thirds of the patients. (3) Affected joints included the hand, wrist, elbow, shoulder, knee, and ankle. (3) Other reported findings in EF include arthritis, inflammatory arthritis, and carpal tunnel syndrome. (2)(3)The differential diagnosis includes scleroderma and sclerodermalike disorders. Misdiagnosis is common in EF. In a case series of 12 patients with EF, all patients had been given other initial diagnoses, and the patients studied had visited an average of 2.4 physicians, ranging from 1 to 7, before being diagnosed as having EF. (3) One case series found that the most common misdiagnosis of EF was diffuse systemic sclerosis (SSc), which also presents with induration of the extremities. (4) However, distinguishing between EF and SSc is critical to guide medical management. A high dose of pulse corticosteroids is first-line treatment in EF, and although it can be used in SSc, there is high risk of renal crises in these patients. EF is a rare disorder and presents rather acutely and with symmetrical swelling and induration of extremities, which is an important distinguishing feature from localized linear scleroderma, which would be unilateral to 1 site. Key clinical findings that would point toward SSc are sclerodactyly, Raynaud phenomenon, and nail-fold capillary changes. Although MRI can show fascial inflammation, full-thickness biopsy of the skin and subcutaneous tissues remains the gold standard for diagnosis of EF. Biopsy in EF shows thickening and fibrosis of the fascia with inflammatory infiltrate of lymphocytes, histiocytes, plasma cells, and eosinophils. (5)Prompt initiation of systemic corticosteroids remains first-line treatment for EF and should result in rapid decrease in eosinophilia. However, if long-term treatment is required, combination with methotrexate may spare the amount of corticosteroids required. (4)Our patient originally presented with unilateral contractures that led to his toe-walking. Although EF usually presents bilaterally, it is important to consider even with unilateral findings in the setting of typical laboratory findings. In this case, although skin findings and contractures were unilateral, MRI did reveal the bilateral fascial involvement expected with EF.During the next 2 weeks, he continued to have ongoing changes of skin tightening and firmness up the posterior thigh and buttock, with new skin tightening on his left leg. He also developed bilateral wrist swelling, pain, and limited flexion and extension with mild tightening of forearms. Given the severity and rapid progression of symptoms, a 5-dose series of intravenous methylprednisolone 1,000 mg was started urgently, followed by twice daily oral prednisone 30 mg and topical calcipotriene. The eosinophil count dropped rapidly to 526/μL (0.526 × 109/L; 6.3%) after 2 days of corticosteroid therapy and 62/μL (0.62 × 109/L; 5.7%) after 7 days. Disease progression slowed on oral prednisone, but given significant adverse effects, methotrexate was added as a corticosteroid-sparing and anti-inflammatory agent. At the 3-month follow-up visit, the eosinophil count was normal, but there was still significant tightening of the skin. By the 10-month follow-up visit, there was noticeable skin softening (Fig 7).Thank you to Dr Amy Davis for providing histopathologic images and interpretations of biopsy findings and to Dr Crystal Farrell for help with obtaining and interpreting the magnetic resonance images.