Multisystem Disease
Multisystem Disease
This domain tests systemic diseases with characteristic multiorgan imaging: sarcoidosis, tuberculosis, vasculitis, connective tissue disease, neurocutaneous syndromes, lymphoma, and metastatic disease. Pattern recognition across systems is key.
Core rules
- Sarcoidosis: bilateral symmetric hilar lymphadenopathy, perilymphatic nodules, erythema nodosum, and elevated ACE; it may involve liver, spleen, heart, and CNS.
- Tuberculosis: upper-lobe cavitation, miliary nodules, pleural effusion, and necrotic lymphadenopathy; it disseminates in immunocompromised patients.
- Vasculitis: Takayasu affects the aorta and branches with wall thickening; ANCA vasculitis causes pulmonary hemorrhage and glomerulonephritis; polyarteritis nodosa causes microaneurysms.
- Neurocutaneous: neurofibromatosis type 1 has optic pathway gliomas and neurofibromas; tuberous sclerosis has cortical tubers, subependymal nodules, and renal angiomyolipomas.
Worked example
A 30-year-old woman has bilateral hilar lymphadenopathy, erythema nodosum, and arthralgia. The combination suggests sarcoidosis (Löfgren syndrome). If CT shows perilymphatic nodules along bronchovascular bundles, the diagnosis is supported. Lymphoma would more often show bulky asymmetric adenopathy.
Traps
Calling sarcoidosis without considering lymphoma or TB; missing cardiac sarcoidosis on MRI; overlooking renal angiomyolipomas in tuberous sclerosis; attributing multiorgan disease to metastases without a primary; ignoring occupational exposure history.