Pulmonary hematoma is defined as the presence of blood within the alveolar and interstitial spaces . In general, the pulmonary hematoma is caused by chest trauma. However, rare cases without a previous history of trauma have been reported, when the condition is referred to as spontaneous or idiopathic pulmonary hematoma. Anticoagulant therapy, thrombocytopenia, and rare diseases such as Ehlers-Danlos syndrome are some of the presumed causes of spontaneous or idiopathic pulmonary hematoma [1,2,3,4,5,6,7]. In our case, there was no history of trauma and no history of anticoagulant therapy, and his coagulation profile was normal. In addition, the pathogenesis remained unclear. Therefore, we diagnosed the case as a rare case of spontaneous pulmonary hematoma.
A noteworthy feature of this patient was that the histopathology revealed multiple ossified areas with bone marrow formation within the hematoma. Such a condition is called diffuse pulmonary ossification (DPO). While this condition has not previously been reported to be associated with intrathoracic bleeding, there is a possibility that it was associated with the intrathoracic bleeding in some way in our present case.
DPO is a rare disease that is characterized by diffuse and ectopic ossification in the lung tissue, and was first reported by Luschka in 1856 . DPO has been classified into two subtypes: the nodular and dendriform types of DPO. Of the two types, dendriform pulmonary ossification is the less common. Nodular DPO usually occurs in situations of chronic congestion, such as mitral valve stenosis. On the other hand, dendriform DPO occurs secondary to acute or chronic damage of the lung, such as idiopathic pulmonary fibrosis, acute respiratory distress syndrome, and chronic obstructive pulmonary disease [9, 10]. In the case reported herein, the ossification was of the dendriform type; however, no abnormalities were observed in the background lung, and the cause of the ossification remained unclear. Since DPO is usually asymptomatic, as per most previous case reports, the condition is usually discovered accidentally at autopsy and rarely during the life of the patient. Furthermore, a literature search to the best of our ability revealed no previous report of pulmonary hematoma with DPO associated with intrathoracic bleeding requiring emergency surgery, as in this case; therefore, this was a very rare and interesting case. We think that the hemorrhage continued to occur as a result of a vessel rupture, so that the hematoma increased in size and the visceral pleura tore due to the pressure exerted by the hematoma.
Patients with pulmonary hematoma without a previous history of trauma are often asymptomatic; however, some cases may present with symptoms such as hemoptysis .
Because pulmonary hematoma is visualized as an opacity on imaging examinations, it is often difficult to distinguish it from malignancy. However, pulmonary hematoma usually disappears spontaneously from 3 weeks to 3 months, in the absence of any special complications [7, 11]. Therefore, in the absence of any serious symptoms and the presence of sufficient evidence to suspect pulmonary hematoma, such as a previous history of trauma, the management would be conservative. It is important to conduct further evaluation for the possibility of malignancy if the opacity is found to increase in size on follow-up examinations. In addition, in recent years, chest magnetic resonance imaging has also been shown to be useful for the diagnosis of pulmonary hematoma, and especially for distinguishing hematoma from malignancy .
No specific treatment or management for DPO has been established, but in asymptomatic cases, or aggressive treatment is necessary. Regular follow-up with respiratory function testing and imaging examinations is recommended .
The patient reported here is currently under observation as an outpatient, and a follow-up chest X-ray has shown no evidence of recurrence. However, as the cause remains unclear, bearing in mind the possibility of appearance of new lesions/recurrence, we propose to keep the patient under careful follow-up.