System

Differential Diagnosis

Common Presentation

Investigation

Likelihood in our Patient

Treatment

Neurology

Posterior Fossa Malignancy

-Head-tilt

-Headache

-Herniation (respiratory depression, bradycardia)

-CT and MRI of the brain

Unlikely - repeat exam noted bilateral foot clonus, ataxic gait and left-sided head tilt, but imaging negative

-Surgery

-Chemotherapy and Radiation

Hematology/Oncology

Lymphoma

-Night sweats

-Pruritus

-Weight loss

-Cough

-Lymphadenopathy (non-tender)

-CBC (normal or high WBC)

-Bone marrow biopsy

-Chest x-ray

-Excision of the lymph node

Unlikely - patient had regional tender lymphadenopathy, no history of cough, weight loss or night sweats

-Chemotherapy and Radiation

-Surgery

Leukemia

-Bone pain

-Weight loss

-Fever

-Poor appetite

-Bleeding

-Bruising

-Infections

-CBC (high or low WBC, low Hb or Plt)

-BMP (high potassium)

-LDH (elevated in Tumor Lysis Syndrome)

-Uric Acid (Elevated in Tumor Lysis Syndrome)

-Bone marrow biopsy

Unlikely - normal white count, slightly elevated LDH to 359, normal uric acid, no weight loss, or change in appetite

-Chemotherapy (induction and maintenance)

Neuroblastoma with osseous metastases

-Nystagmus

-Purple hue to eyelid

-Possible ecchymosis to periorbital area

-Abdominal Pain

-Elevated ferritin

-Elevated LDH

-Urine VMA may be elevated

-Bone Marrow Biopsy

-CT/MRI

-MIBG scan

Likely - given age and sex, but without abnormal eye movements, abdominal pain, and abdominal imaging negative for mass

-Surgical Resection

-Chemotherapy

-Radiation

-Antibody medicines (Naxitamab or Omburtamab)

Spinal Tumor

-Back Pain

-Neuropathy from compression

-Incontinence

-Ataxic Gait

-CT and MRI of the spine

Less likely - given age, no incontinence, although patient had back pain and ataxic gait

-Surgery

-Chemotherapy

-Radiation

Infectious Disease

Cat-Scratch Disease

-Regional lymphadenopathy +/- drainage

-Fever

-Scratches or bites

-Back Pain

-Bartonella IgM Serology

Likely - had point tenderness at T2, pustule on left heel from first ER visit, left groin lymphadenopathy, possible cat exposure at home, CT showed enhancement at T2

-No need to treat, unless patient is immunocompromised or with severe disease

-Treat with macrolides, doxycycline, TMP-SMX, and gentamicin

Tuberculosis (Pott’s Disease)

-Cough

-Night sweats

-Hemoptysis

-Fever

-Back Pain

-Spinal deformity

-Positive QuantiFERON-Gold test

-AFB smears of sputum/secretions

-Positive PPD

Unlikely - chest xray and initial spinal imaging negative, no history of exposure, negative quantiferon

-Rifampin

-Isoniazid + pyridoxine (for possible neuropathy)

-Ethambutol

EBV

-Sore throat

-URI symptoms

-Fatigue

-Abdominal Pain

-Fever

-Lymphadenopathy

-Viral Capsid Antigen

-Monospot

-EBV IgM and IgG titers

-CBC (atypical lymphocytes)

Unlikely - patient had regional lymphadenopathy only, no URI symptoms or abdominal pain, EBV serology negative

-Supportive care

CMV

-Sore throat

-URI symptoms

-Fatigue

-Abdominal Pain

-Fever

-Lymphadenopathy

-CMV IgM and IgG titers

Unlikely - Patient had regional lymphadenopathy only, no URI symptoms or abdominal pain, and CMV serology negative

-Supportive care