Differential Diagnosis

The patient presents with elevated eosinophils, elevated absolute monocytes, decreased lymphocytes, joint pain, cough, and low-grade fever. Here's a categorized differential diagnosis:

• Single Most Likely Diagnosis

  • Churg-Strauss Syndrome (Eosinophilic Granulomatosis with Polyangiitis, EGPA): This condition is characterized by asthma, eosinophilia, and vasculitis affecting multiple organ systems. The combination of elevated eosinophils, joint pain, cough, and low-grade fever makes EGPA a strong consideration. The presence of monocytes could be indicative of an inflammatory response.

• Other Likely Diagnoses

  • Parasitic Infections: Certain parasitic infections, such as hookworm or strongyloidiasis, can cause eosinophilia. The presence of joint pain and cough could be related to a systemic infection.
  • Hypereosinophilic Syndrome (HES): This is a group of disorders characterized by the overproduction of eosinophils, leading to organ damage. Patients with HES can present with a variety of symptoms, including joint pain and respiratory issues.
  • Sarcoidosis: Although more commonly associated with an elevated lymphocyte count, some patients with sarcoidosis can have eosinophilia. The disease can cause joint pain, cough, and fever, among other symptoms.

• Do Not Miss Diagnoses

  • Lymphoma: Certain types of lymphoma, such as Hodgkin lymphoma, can present with eosinophilia and decreased lymphocytes. It's crucial to consider lymphoma due to its potential for severe consequences if left untreated.
  • Acute Eosinophilic Pneumonia: This is a rare but potentially life-threatening condition that requires immediate attention. Patients typically present with respiratory symptoms, fever, and eosinophilia.

• Rare Diagnoses

  • Eosinophilic Granuloma with Polyangiitis (formerly known as Churg-Strauss Syndrome, but without the asthma component): A variant of EGPA without asthma, which could still present with eosinophilia, joint pain, and systemic symptoms.
  • Idiopathic Eosinophilic Fasciitis: A rare condition characterized by eosinophilia and inflammation of the fascia, which could cause joint pain and systemic symptoms.
  • Loeffler's Syndrome: A type of pulmonary eosinophilia that can cause respiratory symptoms and eosinophilia, often associated with parasitic infections or drugs.