1. Multiple Sclerosis (MS):

   • Presentation: Neurological deficits (e.g., optic neuritis, sensory loss, motor weakness, diplopia, vertigo) that are separated in time and space. The classic relapsing-remitting form involves episodes (flares/waxing) of neurological dysfunction followed by periods of partial or complete recovery (remission/waning).
   • Why High Yield: Classic autoimmune demyelinating disease, tests concepts in neurology, immunology, and pathology.

2. Systemic Lupus Erythematosus (SLE):

   • Presentation: A multi-system autoimmune disease characterized by flares (waxing) involving various organs (skin rash, arthritis, nephritis, serositis, hematologic abnormalities) followed by periods of relative quiescence (waning), though often with underlying chronic activity.
   • Why High Yield: Prototypical systemic autoimmune disease, tests immunology (Type II & III hypersensitivity), multi-organ pathology.  

3. Myasthenia Gravis (MG):

   • Presentation: Muscle weakness, particularly affecting ocular (ptosis, diplopia) and bulbar muscles, that worsens with repeated use throughout the day (waxing) and improves with rest (waning).
   • Why High Yield: Tests neuromuscular junction physiology, autoimmunity (anti-AChR antibodies), pharmacology (acetylcholinesterase inhibitors).

4. Inflammatory Bowel Disease (IBD - Crohn’s Disease & Ulcerative Colitis):

   • Presentation: Chronic inflammatory conditions of the GI tract characterized by periods of active inflammation (flares/waxing - diarrhea, abdominal pain, bleeding) interspersed with periods of remission (waning).
   • Why High Yield: Common GI pathology, tests immunology, pathology, and distinguishing features between Crohn’s and UC.

5. Gout:

   • Presentation: Episodic attacks (flares/waxing) of severe, acute arthritis (often podagra - big toe) due to monosodium urate crystal deposition, followed by asymptomatic intercritical periods (waning).
   • Why High Yield: Tests concepts in biochemistry (purine metabolism), pathology (crystal arthropathy), pharmacology (treatments like NSAIDs, colchicine, allopurinol).

6. Follicular Lymphoma:

   • Presentation: Often described as an indolent (slow-growing) non-Hodgkin lymphoma. Patients may present with painless lymphadenopathy that can spontaneously increase and decrease in size over months or years, even without treatment (waxing and waning lymph node size).
   • Why High Yield: Tests hematology/oncology concepts, specific translocation t(14;18), BCL-2 overexpression, histology.

7. Hodgkin Lymphoma (Pel-Ebstein Fevers):

   • Presentation: While not the entire disease course, a subset of patients with Hodgkin Lymphoma experience Pel-Ebstein fevers: cyclical fevers that increase (waxing) for several days to weeks, followed by afebrile periods (waning) of similar duration. This specific symptom waxes and wanes.  

   • Why High Yield: Classic hematologic malignancy, Reed-Sternberg cells, distinct subtypes, constitutional “B symptoms” (fever, night sweats, weight loss).