Volume 5, Case 12
Rodney B. Boychuk, MD
Kapiolani Medical Center For Women And Children
University of Hawaiʻi John A. Burns School of Medicine
This 2-year old female was in her usual state of good health until one month prior, when she began complaining of generalized abdominal pain. The "pain spasms" occurred every 15-20 minutes, which would cause her to "double over"; the pain would then gradually subside. At that time, she was seen in the emergency department, where abdominal radiographs revealed moderate gas throughout the bowel and a stool-filled colon. An enema resulted in the passage of large amounts of stool, and the pain seemed to improve. About one week ago (three weeks later), her pain became severe again and, at this point, she refused to walk. Her parents noticed that her knees would shake when she stood up, and she appeared knock-kneed. For the last 3 days, these episodes have intensified, with each episode lasting approximately 5 minutes and returning every 15-20 minutes. Her temperature ranged from 37.3 to 38.6 degrees. She was noted to be more agitated at night and was unable to sleep because of pain. She also seemed to favor her right leg. There was no nausea, vomiting, diarrhea, cough, rhinorrhea or other symptomatology.
Exam: VS T40.3, P160, RR 46, BP 124/65. She appears tired, but otherwise well-developed and well-nourished. She is somewhat irritable but cooperative. She is in the 50th percentile for height, weight and head circumference. HEENT no abnormalities detected. Neck supple without adenopathy. Heart regular without murmurs. Lungs clear. Abdomen is soft without definite tenderness. Bowel sounds are active. No rebound. No organomegaly. No hernias. Small 1 cm lymph nodes are palpable in both inguinal regions. There is tenderness to palpation in the right hip area. Range of motion about this hip is good; however, she fusses when this is done. There does not appear to be any pain with palpation of the pubis, and she is able to log roll normally. There are no other bony or joint abnormalities noted.
Initial labs revealed a white count of 21,700 with 60% neutrophils, 6% bands, 25% lymphs, 8% monos, and 1% eos. Hgb 12.3, Hct 37.2. Platelet count 295,000. Her ESR is 42. Chemistry panel shows a slightly increased LDH at 382 and slightly increased alkaline phosphatase at 212. Radiographs of the abdomen and pelvis are ordered.
View abdominal flat plate.
View pelvic radiographs.
A previous abdominal series done one month ago showed a lot of stool. The overall abdominal gas pattern is non-specific and largely unchanged from the previous radiographs one month ago.
The radiograph of the pelvis appears fairly normal at first glance. Examine the bones carefully to see if you can detect any abnormalities.
This pelvis shows cortical thickening and sclerosis of the right superior pubic ramus. Compare the right and the left sides. You can see that the right superior pubic ramus is hyperdense and irregular. This finding can also be appreciated in retrospect on the abdominal film as well. The radiologist feels that this could be secondary to a low-grade infection, the healing phase of histiocytosis, or a malignancy.
A CT scan of the abdomen showed no other abnormalities. It confirmed the slight cortical sclerosis and thickening of the right superior pubic ramus seen on the plain radiographs.
A radionuclide bone scan was ordered.
View bone scan.
There is intense uptake in the right superior pubic ramus. The differential includes malignancy versus infection. The L1 vertebral body is abnormal in that the left lateral aspect of it appears to be "cold".
In the operating room, an open biopsy was sent for histology and culture. A frozen section of curettings was read as "possible tumor". The cultures returned negative and the final histology was read as chronic inflammation and fibrosis.
She was continued on antibiotics for suspected osteomyelitis. However, she did not improve and her fever worsened. A bone marrow aspiration was performed which showed an unusual type of acute leukemia.
Discussion
Skeletal changes that occur in leukemia are due to infiltration of the bone by proliferating white cells. Characteristically, zones of rarefaction with subperiosteal new bone formation in the metaphyseal region of the humerus or femur, or in the pelvis or spine, are also seen. Occasionally, there is a widespread, diffuse rarefaction of the skeleton (1).
Lucent metaphyseal bands are said to be characteristic of leukemia; however, Rogalsky, et al (3) found lytic lesions in 19%, sclerotic lesions in 4%, and periosteal new bone formation in 2%.
In the younger child, an irregular lytic lesion and/or the presence of periosteal new bone, with or without a lytic lesion, should always suggest osteomyelitis, metastatic neuroblastoma, and eosinophilic granuloma, along with leukemia (6). In the older child and adolescent, various forms of subacute osteomyelitis most often mimic tumors (6).
Osteomyelitis is an inflammation of the bone. Petrola and Vahvanem (5) consider the diagnosis established when 2 of the 4 following criteria are present: 1) Pus aspirated from bone; 2) Positive bone or blood culture; 3) Classic symptoms of localized pain, swelling, warmth, and limited range of motion of the adjacent joint; and 4) Radiographic changes characteristic of osteomyelitis.
When these criteria are not met, it is helpful to remember those conditions that may mimic osteomyelitis and therefore be mistaken for such (6). Trauma may be the most common. It shares some clinical features with osteomyelitis, including pain, tenderness, swelling, and soft tissue swelling on radiographs. Trauma pain improves with time, whereas osteomyelitis worsens. Another differentiating feature is the ESR, which is elevated with osteomyelitis, but normal with trauma.
Neoplasms may mimic osteomyelitis. Leukemia is the most common malignancy in childhood, with bone pain being the presenting sign in about 30% (2). Other non-specific symptoms, such as fever, lethargy, and an elevated ESR and WBC are often present as well. When considering leukemia, other signs and symptoms must be aggressively sought: bone pain in multiple sites, easy bruising, bleeding, a low white blood cell count, anemia, thrombocytopenia, etc.
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