Unexplained Weight Loss with Lymphadenopathy: Diagnostic Considerations

Significant unintentional weight loss (50 lbs/3 months) with regressing lymphadenopathy (10 → 2 cm) and negative biopsy is a complex clinical picture requiring systematic evaluation.

Differential Diagnosis

Category	Conditions	Key Features
Malignancy	Lymphoma (early/treated), occult solid tumor, leukemia	Biopsy false-negative possible (sampling error, prior steroids); PET-CT may reveal active sites
Infection	TB, HIV, EBV/CMV, bartonellosis, fungal	Weight loss from cytokine-driven catabolism; nodes may regress with immune control
Autoimmune/Inflammatory	Sarcoidosis, IgG4-related disease, SLE, Still’s disease	Fluctuating nodes; weight loss from chronic inflammation
Endocrine/Metabolic	Hyperthyroidism, adrenal insufficiency, diabetes	Hypermetabolism; nodes reactive
GI/Malabsorption	Celiac, Crohn’s, chronic pancreatitis, SIBO	Weight loss primary; mesenteric adenopathy possible
Medication/Toxin	Chemotherapy, immunotherapy, stimulants	Temporal association

Recommended Workup

• Repeat imaging (PET-CT or contrast CT neck/chest/abdomen/pelvis).
• HIV, Quantiferon, EBV/CMV PCR, ACE, SPEP, TSH, cortisol, celiac panel.
• Consider excisional biopsy of most accessible node if core/FNA negative and suspicion persists.
• Multidisciplinary review (hematology, ID, rheumatology).

Do not delay; 50-lb loss in 3 months is a high-acuity red flag.