Acute rheumatic fever is a diffuse inflammatory process involving the connective tissues that appears in approximately 0.3 percent of untreated patients suffering infections of the upper respiratory tract by the group. A beta-haemolytic streptococcus. Its importance stems from its morbidity and sequels rather than its mortality.^1–5 Minor manifestations, such as rheumatic pneumonia, epistaxis, and abdominal pain^{1, 5} are relatively non-specific, but are recognised as enhancing diagnostic suspicion. Sometimes, however, patients are admitted to hospital with particularly minor symptoms, which may be unusual.⁶ It is axiomatic that the disease can only be diagnosed when it is suspected. In this light, we report here two interesting cases with very unusual presentations.

Case 1

The patient, a 12-year-old girl, had developed fever, a sore throat, and silent abdominal pain one week previously. Her infection of the upper respiratory tract had been treated for four days with amoxicillin-clavulanate. She was admitted to our hospital with severe abdominal pain, albeit without diarrhoea or vomiting.

On admission, she had a persistent sinus tachycardia, at 136 beats per minute, but was normothermic, at 37.8 degrees centigrade. Her blood pressure was 140 over 80 millimetres of mercury. On examination, we noted periumbilical abdominal tenderness. There were no audible cardiac murmurs, and no swollen joints. The rest of the physical examination was within normal limits. An abdominal ultrasonic examination revealed an oedematous and enlarged vermiform appendix. Appendectomy was done. Pathological sampling confirmed the presence of appendicitis and local peritonitis (Fig. 1). A few days later, her ankles became red, warm, swollen and painful, permitting only a limited range of movement. The changes in the ankles spontaneously disappeared on the second day. Her temperature was then 38.3 degrees centigrade, and she had a pansystolic murmur, of grade 2 or 3 out of 6, audible at the apex and radiating to the left axilla, along with an early diastolic murmur heard at the left side of the sternum. Laboratory evaluations revealed haemoglobin of 9.7 grams per decilitre; the white blood cell count at 12,600 per cubic millimetre, with 60 percent polymorphonuclear cells; a platelet count of 615,000 per cubic millimetre; titres of antistreptolysin O at 1660 international units; levels of C reactive protein at 183 milligrams per decilitre, and an erythrocytic sedimentation rate of 117 millimetres per hour. Other laboratory studies, including the electrocardiogram, were normal. Cross-sectional and Doppler echocardiography demonstrated second degree mitral insufficiency, first degree aortic insufficiency, but normal left ventricular systolic function. The cultures of the throat, urine and blood were negative. On the basis of these findings, we diagnosed acute rheumatic fever with carditis, and we commenced therapy with prednisolone and prophylactic benzathine penicillin. She was discharged from hospital in good condition, albeit still with aortic and mitral insufficiency.

Figure 1. The pathology specimen from our first patient shows massive polymorphonuclear lymphocytic infiltration through the muscular layers of the vermiform appendix. Haematoxylin eosin, with magnification by 100.

Case 2

A 12-year-old boy presented with a low grade fever and pain in his left knee. A few days later, he noted that both knees had become warm, swollen and painful. He also complained of pain in the lower back and chest. On examination, his vital signs were normal. His left knee was warm and tender, albeit with a full range of motion. A pansystolic murmur, graded at 2 out of 6, was heard at the apex. Laboratory studies showed haemoglobin at 11.6 grams per decilitre; a white blood cell count of 9,940 per cubic millimetre, with 70 percent polymorphonuclear cells; a platelet count of 483,000 per cubic millimetre; a titre of antistreptolysin O at 499 international units, C reactive protein at 118 milligrams per decilitre, and an erythrocytic sedimentation rate of 76 millimetres per hour. Culture of the throat proved negative. An electrocardiogram revealed second degree Mobitz I atrioventricular block (Fig. 2). The chest X-ray was normal, but echocardiography revealed second degree mitral insufficiency.

Figure 2. The electrocardiogram of our second patient, on admission, showed second degree Mobitz I atrioventricular block.

Since the clinical and laboratory findings satisfied the Jones criterions for the diagnosis of acute rheumatic fever and carditis, we commenced treatment with prednisolone and prophylactic benzathine penicillin. The patient improved dramatically. Within two days, he was able to walk without pain and his electrocardiogram had reverted to normal. A week later, acute phase reactants were normal. He was discharged on prednisolone for six weeks, along with three weekly injections of benzathine penicillin.