대한흉부영상의학회 Korean Society of Thoracic Radiology

Discussion

Diagnosis With Brief Discussion

Diagnosis

Tuberculosis and Empyema necessitatis (tuberculous empyema)

Radiologic Findings

Chest PA (Fig. 1) shows ill-defined mottled density on left upper lobe, and irregular nodular lesion on left infrahilar area. There shows pleural based mass on left lower lateral lung base. CT shows irregular mass with inner cavity on left apex (Fig. 2) and rectiangular shaped nodule on left lingular segment (Fig. 3, 4). Another small nodules are visible on right upper posterior and left posterior lingular segments. There shows pleural and extrapleural low density mass and focal rib erosion (Fig. 5). The mass is slight peripheral rim enhancement, and another subpleural low density mass on anterior aspect.
Chest PA after 7 days (Fig. 6) shows no interval change of left upper and infrahilar opacities. Focal left 8th rib is resected, and still visible pleural based mass lesion on left lower lateral lung base.

Brief Review

Empyema necessitatis is a collection of inflammatory tissue that usually extends directly from the pleural cavity into the thoracic chest wall forming a mass in the extrapleural soft tissues, following anatomic boundaries.
It is an uncommon complication of pleural empyema. Mycobacterium tuberculosis is the most frequent cause and is responsible for 73% cases of empyema necessitatis. Rarer causes of it include pyogenic lung abscesses (due to S. pneumoniae, Staphylococcus species, gram-negative bacilli, and polymicrobial infections), blastomycosis, actinomycosis, malignancy or lymphoma. The empyema may also extend into the paravertebral soft tissues, vertebral column and rarely the esophagus and the pericardium.
Radiography shows a soft tissue mass in the chest wall with or without bony destruction. Typical CT findings include a thick-walled, well-encapsulated pleural mass associated with an extrapleural mass in the chest wall.
The association of malignancy with long-standing pleuritis or empyema, especially tuberculous empyema, is not extremely rare. As for non-Hodgkin malignant lymphoma, Luchi et al reported that it occurred in 2.2% of patients with chronic empyema. To differentiate the malignancy from exacerbation of the empyema, it is more important to examine the shape of a mass with soft-tissue attenuation, irregularity of the thickness of the wall, and existence of projections in the cavity. Another helpful CT finding for differential diagnosis is bony destruction. Bony destruction caused by lymphoma is not uncommon and usually shows permeative patterns of destruction, whereas bony destruction caused by osteomyelitis in empyema necessitatis is rare and usually shows osteolytic and expansile pattern destruction. This case shows multiple tuberculomas and tuberculosis with empyema on left lower posterolateral thorax.

References

1. Bhatt GM, Austin HM. CT demonstration of empyema necessitates. J comput assist tomorgr 1985;9:1108-1109
2. Gibbens DT, Argy N. Chest case of the day: tuberculosis empyema necessitatia. AJR 1991;156:1295-1296
3. Minami M, Kawauchi, N, Yoshikawa K, et al. Malignancy associated with chronic empyema: radiologic assessment. Radiology 1991;178:417-423
4. Kim YK, Lee SW, et al. A case of pyothorax-associated lymphoma simulating empyema necessitates. J of clinical imaging 2003;27:162-165

Keywords

Lung, Infection, Bacterial infection, Tuberculosis,