Mr. P. is a 39-year-old city worker with unremarkable past medical history except for “asthma.” He started to experience vague abdominal and low back pain and was initially treated by his family physician with analgesics and Arthrotec, bringing some relief. He underwent an abdominal ultrasound and an IVP (intravenous pyelogram) and both were unremarkable except for “fatty liver.” A fortnight later he presented to the emergency department with ongoing symptoms of pain radiating to both legs.
The ED doctors suspected discogenic back pain. Mr. P. was given Flexeril (cyclobenzaprine) and Tylenol #3 as required and discharged home. But 2 weeks later, he presented to the ED at midnight complaining of shortness of breath. He was “seeing stars,” he said, and felt his asthma was “acting up” with ongoing vague symptoms of abdominal pain and bloating and not getting enough air. He felt no chest pain or tightness. He denied symptoms of cough, phlegm or hemoptysis. He’d felt little appetite for a week, but denied symptoms of heartburn, reflux, nausea or vomiting. He’d been constipated for a few days but there was no bleeding per rectum or melena. He denied symptoms of fever but had felt chills and night sweats over the past fortnight. He’d lost 2-3 kg in the past month.
Mr. P.’s a smoker with a 15 pack-year history, and a social drinker. His medications were ventolin PRN, Tylenol #3 as required and Flexeril 10 mg twice a day.
Physical examination revealed a gentleman of stated age, in no acute distress with blood pressure of 130/78 and regular rhythm. He was afebrile. Head and neck examination was unremarkable and neck was supple. There was no lymphadenopathy or bruits. Chest was resonant with increased expiration without crackles or wheezes and normal heart sounds. Abdomen was soft and slightly distended, with mild vague tenderness without rebound. There were no masses, no renal angle fullness or tenderness. There was no pedal edema or calf tenderness. Neurological examination was non-focal. The examination of the back was unremarkable and there wasn’t any spinal tenderness.
An ECG was normal and a urinalysis negative. A chest X-ray showed plate-like right lower lobe atelectasis. An arterial blood gas showed a pH of 7.38, pCO2 of 18, pO2 of 90, bicarbonate 11 and SaO2 of 97% on room air.
What’s wrong with this man?
Laboratory data was as follows
Mr. P. presents with 6 weeks’ history of vague lower back pain, treated with analgesics, anti-inflammatory agents and muscle relaxants, and now reports difficult breathing and seeing “stars” (likely because of hyperventilation).
He’s noted to have slightly elevated ESR and LDH, and low bicarbonate with elevated anion gap of 17 and respiratory alkalosis (pCO2 is lower than the expected 25 for a bicarbonate level of 11) with metabolic acidosis of both anion and non-anion gap type (serum bicarbonate is lower than accounted for by increase in anion gap).
The differential diagnosis is wide and includes pulmonary embolism (dyspnea, elevated LDH, respiratory alkalosis), inadvertent aspirin intoxication, bowel infarction or intra-abdominal pathology including a neoplastic process involving pancreas or bowel. A helical CT chest ruled out pulmonary embolism, and salicylate levels were normal. A CT scan of abdomen showed extensive matting of bowel loops and he underwent an emergent laparotomy that confirmed matted bowel loops and “caked” abdomen. Bowel loops and mesentery were covered with small nodules. The biopsy showed a diffuse infiltrate with a starry sky pattern in mesenteric fat, omentum and small bowel, findings consistent with Burkitt’s lymphoma. Mr. P. was transferred to a tertiary care centre for management of high-grade lymphoma.
Burkitt’s lymphoma is a high-grade B-cell lymphoma that occurs in endemic or sporadic forms. It’s most common in children, but may occur in adults and accounts for 2% of all B-cell tumours. It’s rare in North America but endemic in Africa. It’s characterized by small non-cleaved cells, uniform in appearance, that produce a diffuse pattern of tissue involvement and give a “starry sky” appearance under the microscope. The Epstein-Barr virus (EBV) has been strongly implicated in the endemic African form, and is associated with about 20% of sporadic cases. Rare adult cases are associated with immunodeficiency, particularly AIDS.
The endemic form often involves the maxilla or mandible, while involvement of abdominal organs is slightly less common. In contrast, the sporadic form usually involves abdominal organs, most commonly the distal ileum, cecum, or mesentery. Before aggressive therapeutic regimens were developed, mortality was high. With combination chemotherapy and CNS prophylaxis, the survival rate is now at least 60%. Patients with limited disease have a survival rate of 90%. Those with bone marrow and CNS involvement have a poor prognosis.
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