Unexplained Fever

Basic Principles

Principal signs and symptoms: malaise; undulating subfebrile temperatures are most common, but fever may occur. Hematologic changes, anemia, elevated ESR. Weight loss, night sweats; constipation or diarrhea, or an alternation of both.

ESR. Weight loss, night sweats; constipation or diarrhea, or an alternation of both.
Diagnosis:
x Basically, all infectious diseases should be excluded.
x An occult abscess is frequently responsible for the disease and fever. A systematic search should be conducted and may include CT scans if required.
x Virtually any tumor may cause unexplained fever.
x If enlarged lymph nodes are found, the anatomy of the lymphatic drainage
pathways can help direct the search for a primary tumor

Visceral lymph node metastases and their relationship to primary
tumor sites

	Sites of nodal metastases	Primary tumor sites
	Inferior mesenteric lymph nodes	Left side of the colon, sigmoid colon
	Superior mesenteric lymph nodes	Right side of the colon, small intestine, pancreas
	Celiac lymph nodes	Lower esophagus, stomach
	Lymph nodes at the porta hepatis	Lower esophagus, stomach, colon, liver, gallbladder, pancreas, urogenital system

Differential diagnosis of unexplained fever

	Diagnosis	Sonographic signs
	Common
	Gastrointestinal tumors	Hypoechoic round lesions, intestinal target patterns, signs of partial bowel obstruction
	Pancreatic tumor	Hypoechoic mass, dilatation of pancreatic and bile duct
	Abscess	Hypoechoic, sharply circumscribed mass that may show highlevel internal echoes

Differential diagnosis of unexplained fever ñ continued

	Diagnosis	Sonographic signs
	Less common
	Hypernephroma	Nonhomogeneous mass, variable echogenicity, pseudocapsule
	Adrenal tumor	Hypoechoic mass between the vena cava or aorta and the superior renal pole
	Malignant lymphoma	Diffuse organ infiltration or multiple, hypoechoic extra- and intraabdominal round lesions distributed along vascular pathways
	Breast carcinoma	Variable echogenicity, ill-defined margins with tumor extensions, usually a nonhomogeneous internal echo pattern
	Endocarditis	Thickened valves, echogenic deposits, valvular regurgitation
	Rare
	Sarcoma
	Atrial myxoma	Intracavitary echogenic mass, usually very mobile

Conditions that cannot be diagnosed with ultrasound
Common: Central bronchial carcinoma  (chest wall tumors can be detected sonographically
and sampled by ultrasound-guided percutaneous biopsy)

Less common: Leukemia
Rare: Melanoma

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