Differential Diagnosis
- Single most likely diagnosis
- Acute appendicitis: The patient's presentation of a mildly distended, fluid-filled appendix without surrounding inflammatory fat stranding, along with a elevated white blood cell count (WBC 17.1), is highly suggestive of early or developing acute uncomplicated appendicitis.
- Other Likely diagnoses
- Pulmonary infection (e.g., pneumonia): The presence of a 9 mm noncalcified middle lobe nodule with surrounding ground-glass opacity is concerning for a probable infectious or inflammatory process, which could be related to a pulmonary infection.
- Gastroenteritis: Although the appendix is the primary concern, the patient's symptoms and elevated WBC could also be consistent with gastroenteritis, especially if the appendix is not the sole source of infection.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed.)
- Appendiceal rupture or perforation: Although the current imaging does not show overt signs of surrounding inflammatory fat stranding, the possibility of appendiceal rupture or perforation must be considered, as it is a medical emergency requiring prompt surgical intervention.
- Pulmonary embolism: The presence of a middle lobe nodule could be a "masquerader" for a pulmonary embolism, especially if the patient has risk factors for thromboembolic disease.
- Diverticulitis: Although the primary concern is the appendix, diverticulitis could present with similar symptoms and must be considered, especially if the patient has a history of diverticular disease.
- Rare diagnoses
- Neoplastic process (e.g., appendiceal tumor): Although less likely, a neoplastic process affecting the appendix could present with similar imaging findings and must be considered, especially if the patient's symptoms persist or worsen despite treatment for appendicitis.
- Granulomatous disease (e.g., sarcoidosis): The presence of a pulmonary nodule could be related to a granulomatous disease, which, although rare, must be considered in the differential diagnosis.