Minimally invasive approaches for histological diagnosis of anterior mediastinal masses

Anterior mediastinal masses include a wide variety of diseases from benign lesions to extremely malignant tumors. Management strategies are highly diverse and depend strongly on the histological diagnosis as well as the extent of the disease. We reported a prospective study comparing the usefulness of core needle biopsy and mini-mediastinotomy under local anesthesia for histological diagnosis in anterior mediastinal masses.

A total of 40 patients with masses of unknown histology and located either at or near the anterior mediastinum received biopsy prior to treatment. The diagnostic methods were core needle biopsy in 28 patients and biopsy through mini-mediastinotomy under local anesthesia in 15 patients (including 3 patients for whom core needle biopsy failed to yield a definite diagnosis).

Histological diagnosis was achieved in 18 of the 28 patients receiving core needle biopsy. Of them, all 4 patients with pleural fibromas and 9 of the 12 patients (75%) with pulmonary mass were diagnosed definitively. In the remaining 12 patients with mediastinal mass, histological diagnosis was achieved in only 5 patients (41.7%). In contrast, biopsy through a mini-mediastinotomy failed in only 3 patients. In the remaining 12 patients with huge mediastinal masses, who underwent mini-mediastinotomy, a definitive histological diagnosis was reached by pathological and/or immunohistochemical study (diagnostic yield 85.7% in 12 of 14 cases of mediastinal mass, P = 0.038 vs core needle biopsy). For the 9 patients with thymic epithelial tumors, the diagnostic yield was 40% (2 in 5 cases) for core needle biopsy and 83.3% (5 in 6 cases) for mini-mediastinotomy. There was no morbidity in patients receiving mini-mediastinotomy. In the 30 patients with biopsy-proven histological diagnosis, the results contributed to therapeutic decision making in 25 cases (83.3%).

Core needle biopsy is effective in the diagnosis of pulmonary and pleural diseases. Yet its diagnostic yield in mediastinal mass is rather low. Superior to core needle biopsy, biopsy through a mini-mediastinotomy under local anesthesia is highly effective in the histological diagnosis of anterior mediastinal mass, and has a satisfactory diagnostic yield. The method is safe, minimally invasive, cost-effective, and useful in therapeutic decision making for anterior mediastinal masses.