A six-year-old boy with autism and left hip pain

What diagnoses should be ruled out in this patient?

1. Slipped capital femoral epiphysis

2. Septic arthritis

3. Osteomyelitis

4. Malignant disease

5. All of the above

The answer is (e). Multiple conditions may cause hip pain in children, but it is essential to rule out serious conditions, such as those listed above. The radiograph did not show evidence of slipped capital femoral epiphysis, which typically occurs in older children. Legg–Calve–Perthes disease is also an important cause of hip pain, but the presentation is usually more insidious. There was also no avascular necrosis seen on the radiographs, although initial radiographs can appear normal.

Septic arthritis should always be considered in a patient with joint pain, although it is typically more acute in onset and less likely without fever. Osteomyelitis is also less probable in a patient who is afebrile. Malignant disease should be considered in any case of bony pain; about 25% of children with newly diagnosed leukemia present with a complaint of severe bone pain. The patient had no constitutional symptoms, but the parents described “red dots,” which could be indicative of thrombocytopenia in the setting of leukemia.

On physical examination, the patient’s weight was 21.2 kg (25th percentile) and his height was 121 cm (50th percentile). He was afebrile, and vital signs were within normal limits. He appeared pale and sat with his left hip flexed and externally rotated, with flexion of the left knee. He was unable to fully extend his left knee and had discomfort on internal rotation of his left hip. There was no evidence of erythema or warmth, and he had no discomfort on palpation. The range of motion of his right hip and knee were normal, and there were no joint effusions. Hepatosplenomegaly and lymphadenopathy were absent. Dermatologic examination showed palpable petechiae on his arms and legs bilaterally (Figure 2) and some ecchymoses on his legs. The patient had swollen, purple gingiva with blood-filled blisters (Figure 3), which bled spontaneously on examination. His parents reported that these lesions had begun about three months earlier.

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Figure 2:

Palpable petechiae on the patient’s arms and legs, shown here on his left leg.

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Figure 3:

Swollen, purple gingiva with blood-filled blisters.

Results of initial laboratory tests are shown in Box 1.

What is the most likely diagnosis?

1. Leukemia

2. Henoch–Schönlein purpura

3. Bleeding disorder

4. Nonaccidental injury

5. Dietary deficiencies

The answer is (e). Given the patient’s normal leukocyte and platelet counts, and the absence of blasts on peripheral smear, leukemia was not likely. In addition, although the hemoglobin concentration was low, the reticulocyte count was appropriately elevated, which indicated adequate bone marrow function. Henoch–Schönlein purpura can cause both joint pain and palpable purpura without thrombocytopenia; however, the joint pain is typically more acute in onset. In addition, mucosal bleeding and anemia are not characteristic. A bleeding disorder would be less likely in the context of a normal platelet count, and normal international normalized ratio and partial thromboplastin time. Nonaccidental injury should be considered in any case of bony pain and unexplained bleeding, but it was not felt to be the cause in view of the other findings.

Dietary deficiencies should be considered in children presenting with anemia, gingival disease and osteopenia, especially those with autism spectrum disorder, who are more likely to have restrictive diets. A 24-hour dietary recall interview was conducted. We established the percentage of recommended daily intake of vitamins and minerals by looking at the specific brands purchased.

Our patient had a highly restrictive diet, with complete absence of vitamins C and D and only minimal iron intake (Box 2). He had not consumed fruits (other than a few apples) or vegetables in more than three years and was not taking vitamin supplements. He ate the same foods every day, which meant the 24-hour dietary recall reflected his entire diet. At the time of our examination, we learned that a dietitian had started working with the patient to reintroduce fruits and vegetables. Apples were the first fruit reintroduced, several months earlier, but the patient had stopped eating them because of gingival pain.

The combination of bony pain, perifollicular petechial rash, bleeding gums, anemia and no dietary vitamin C is classic of scurvy. To confirm the diagnosis, ascorbic acid measurement was done, as well as iron studies and measurement of vitamins B₁₂ and D (Box 3). Zinc levels were not measured at the time of diagnosis.

Although the patient’s dietary history suggested micronutrient deficiency secondary to restriction, deficiency from malabsorption was also considered. This was thought to be less likely considering the degree of dietary restriction and the absence of gastrointestinal symptoms. The decision was therefore made to start vitamin and mineral supplementation (250 mg of vitamin C and 800 IU of vitamin D once daily, 40 mg of elemental iron and 250 mg of calcium carbonate three times daily, and a multivitamin once daily) and to monitor the patient closely through follow-up appointments to determine the need for further investigations into malabsorption.

Within two weeks, the patient’s hip pain had resolved and his gingival bleeding had greatly improved. Results of repeat laboratory investigations done eight weeks later showed normalization of the erythrocyte sedimentation rate, hemoglobin concentration and vitamin D level (Box 3). Because of laboratory error, the repeat ascorbic acid level is not reported here. The rapid resolution of symptoms and normalization of laboratory values following vitamin and mineral supplementation further indicated that the micronutrient deficiencies were secondary to dietary restriction rather than to malabsorption. No further investigations were pursued.