Infiltrative Diseases
What? Cellular/molecular/granulomatous infiltration of tissue -> (multi)organ dysfunction
Clues? (credit to Dr. Andrew Sanchez, click to see his post on this topic)
Visible Clues
Skin: nodules, rash
HEENT: xanthelasma, proptosis, eyelid and parotid swelling, macroglossia
MSK: painful bone lesions, tendon/ligament ruptures, carpel tunnel
Neuro: peripheral neuropathy, autonomic neuropathy
Lymph nodes: lymphadenopathy
Organs: organomegaly, multifocal masses, "-itis"
Retroperitoneum: ureteral obstruction, hydronephrosis
Vessel: aortitis
Occult clues
Endocrine: Hypopituitarism, hypothyroidism, hypoPTH
Organs: Heart, liver, kidney, adrenal, pancreatic failure
LFTs: ALP > Tbil elevation
Framework? (credit to Dr. Bob Centor and the Clinical Problem Solvers)
Cells
Lymphocytes: Lymphoma (DLBCL), Castleman disease + TAFRO
Plasma cells: AL amyloidosis, Waldenstrom, POEMS
Eosinophils: Hypereosinophilic syndrome
Histiocytes (Macrophages): Langerhans cell histiocytosis, Erdheim-Chester, Rosai-Dorfman, Malignant histiocytosis, HLH
Mast cells: Mastocytosis
Neutrophils/myeloid: VEXAS
Infection:
TB/NTM, Fungal (Histo, Coccidioido, Blasto, Crypto)
Syphilis
"-ellas" bacteria (Bartonella/Brucella/Coxiella/Francisella/Salmonella), Listeria, Actinomyces/Nocardia, Whipple, Melioidosis
Leishmaniasis/Schistosomiasis
CMV/EBV
Autoimmune: Sarcoidosis, IBD (Crohn), PBC; GCA/Takayasu, GPA/eGPA
Immune deficiency: CVID, CGD
Drug: allopurinol, etanercept
Foreign body: silicone, tatto, berryliosis, talc
Molecule
Amyloid: AA amyloid, ATTR amyloid
IgG4: IgG4RD
Iron: Hemochromatosis
Copper: Wilson
Mimic: Myelofibrosis (If pancytopenia + hepatosplenomegaly w/o imaging signs of infiltration, consider myelofibrosis as a mimic. Hepatosplenomegaly is due to compensatory extramedullary hematopoiesis.)