Pulmonary mycetoma

Pulmonary mycetoma refers to a fungal ball — typically composed of Aspergillus species — that colonizes a preexisting pulmonary cavity (such as one formed by prior tuberculosis, sarcoidosis, or bullous emphysema). The fungal mass grows within the cavity without invading surrounding tissue, distinguishing it from invasive aspergillosis. Hemoptysis, which can be massive and life-threatening, is the most common presenting symptom.

Apply this code when documentation confirms a fungal ball within a pulmonary cavity, typically supported by imaging (CT chest showing the classic "air crescent sign" or mobile intracavitary mass) and/or culture/serology confirming fungal etiology. This code is appropriate regardless of whether the mycetoma is symptomatic or an incidental finding. It applies most commonly in patients with a history of cavitary lung disease, immunocompromise, or chronic pulmonary conditions.

• Do not confuse with invasive pulmonary aspergillosis (B44.1) or other forms of pulmonary aspergillosis (B44.-); mycetoma is a non-invasive colonization and has its own distinct classification — verify documentation clearly supports non-invasive fungal ball rather than invasive disease.
• Code the underlying cavitary lung disease separately (e.g., sequelae of tuberculosis, sarcoidosis) as the preexisting cavity is a distinct, reportable condition; sequencing depends on the reason for the encounter.
• Confirm the fungal organism is documented when possible — if the causative organism is specified (e.g., Aspergillus), review whether a more specific code in the B44 category may be more appropriate than this residual/NEC classification.