What is the diagnosis and treatment for a 15-year-old boy with intermittent pain in the right lumbar and right hypochondriac areas, loss of appetite, and bloating, without diarrhea, vomiting, or fever?

Differential Diagnosis and Workup for Adolescent with Right-Sided Abdominal Pain

This 15-year-old boy requires systematic evaluation for serious pathology given the constellation of right lumbar/hypochondriac pain, loss of appetite, and bloating—red flags that warrant imaging despite the absence of fever. 1

Key Clinical Red Flags Present

This patient demonstrates several concerning features that elevate suspicion beyond simple functional pain:

• Loss of appetite (anorexia) - a red flag symptom that increases likelihood of organic disease 2
• Intermittent pain over 4 weeks (implied by "on and off") - constitutes a clinical red flag requiring imaging 3, 1
• Age 15 years - adolescent males have higher risk of serious pathology including neoplasm, infection, and inflammatory conditions 3
• Right-sided location - involves both lumbar spine region and upper abdomen (hypochondriac area), suggesting either spinal pathology or intra-abdominal process 3

Primary Differential Diagnosis

Spinal/Musculoskeletal Pathology

• Infection (discitis/osteomyelitis) - most common in ages 2-12 but can occur in adolescents; presents with persistent pain, decreased range of motion, localized tenderness 3
• Neoplasm - persistent nighttime pain present in 25-30% of children with spinal neoplasm; benign tumors include osteoid osteoma, osteoblastoma, aneurysmal bone cyst 3
• Inflammatory conditions - juvenile idiopathic arthritis, though more common in cervical spine 3

Intra-abdominal Pathology

• Appendicitis (atypical presentation) - loss of appetite is classic, though absence of fever and vomiting is less typical 3
• Sigmoid volvulus - rare but documented in 15-year-old males with intermittent abdominal pain and bloating 4
• Functional abdominal pain - most common cause overall, but presence of anorexia increases organic disease likelihood 2, 5

Immediate Diagnostic Approach

Step 1: Targeted Physical Examination

Perform comprehensive assessment including 1:

• Neurological screening - motor strength, sensory testing, reflexes to identify nerve root compression
• Spinal examination - palpate spinous processes for tenderness, assess curvature and alignment
• Gait testing - abnormalities suggest neurological involvement
• Range of motion - particularly spinal flexion/extension
• Abdominal examination - right lower quadrant tenderness, rebound, guarding, masses

Step 2: Laboratory Testing

Obtain inflammatory markers to assess for infection or inflammatory process 3, 6:

• Complete blood count - leukocytosis suggests infection
• Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) - elevated in infection, inflammation, malignancy

Step 3: Initial Imaging

Anteroposterior and lateral radiographs of the lumbar spine are the appropriate first imaging study 3:

• Useful for evaluating infection, inflammation, or neoplasm in pediatric back pain 3
• Can identify spondylolysis, primary bone tumors, vertebral alignment abnormalities 3
• Critical caveat: Negative radiographs do NOT exclude serious pathology and should not delay advanced imaging if red flags persist 1, 6

Step 4: Advanced Imaging Based on Initial Results

If radiographs are negative but red flags persist:

MRI without and with IV contrast of the lumbar spine is the definitive next step 3, 6:

• Preferred modality for suspected infection (discitis/osteomyelitis, epidural abscess) 6
• Essential for suspected neoplasm 3
• Only modality that directly visualizes spinal cord, ligaments, intervertebral discs 1
• Do not delay this study - imaging should be obtained promptly, not after 4-6 weeks of conservative management 6

Alternative consideration - Bone scan with SPECT/CT 3:

• Highly sensitive (90%) for osseous pathology 3
• Useful if spondylolysis suspected
• Can evaluate entire axial skeleton for multifocal disease 3

If abdominal pathology is more likely based on examination:

Ultrasound of right upper quadrant and right lower quadrant as initial study:

• Non-invasive, no radiation exposure
• Can evaluate for appendicitis, though CT has higher sensitivity 3

CT abdomen and pelvis with IV contrast if ultrasound inconclusive 3:

• Sensitivity 85.7-100% and specificity 94.8-100% for appendicitis 3
• Can identify sigmoid volvulus (swirling mesenteric vessels, dilated sigmoid) 4
• Consider low-dose protocol in adolescents to minimize radiation 3

Critical Management Principles

Do NOT pursue conservative management alone given the presence of red flags 1, 6:

• Loss of appetite with persistent pain warrants investigation for organic disease 2
• Functional abdominal pain diagnosis requires exclusion of organic pathology first 5
• Delay in imaging for serious conditions (infection, neoplasm) can result in catastrophic consequences 3

Urgent referral pathways 6:

• Spine surgery consultation if spinal pathology confirmed
• Pediatric surgery if appendicitis or volvulus identified
• Oncology if malignancy suspected

Common Pitfalls to Avoid

• Assuming functional pain without imaging - presence of anorexia increases organic disease likelihood 2
• Waiting 4-6 weeks for symptom resolution - red flags mandate prompt imaging 1, 6
• Relying solely on negative radiographs - low sensitivity for discitis/osteomyelitis and soft tissue pathology 3, 1
• Anchoring on appendicitis - maintain broad differential including spinal pathology and rare entities like sigmoid volvulus 4
• Obtaining oblique lumbar spine views - doubles radiation without additional diagnostic value 3