Marginal Zone B-Cell Lymphoma (Maltoma)
A low-grade lymphoma, maltoma, represents a form of marginal zone lymphoma arising from mucosal (bronchial) associated lymphoid tissue. Maltomas may arise de novo or be preceded by autoimmune disorders of the lung. Radiographically, maltoma may present as single or multiple nodular masses involving one or both lungs. Airways are usually not affected by these tumors and are likely to remain intact, appearing as air bronchograms on high-resolution CT of the chest. Although not readily visualized endoscopically, a rare maltoma may be diagnosed by endoscopic or transbronchial biopsy. The main histopathologic constituents of maltoma are lymphoid cells resembling small lymphocytes, centrocytes, monocytoid B cells, and lymphoplasmacytic cells, generally with a low level of cellular atypia. An important histopathologic feature of these lesions is involvement of airway epithelium by lymphoid cells, the so-called lymphoepithelial lesion. Cytologically, a mixture of small and large lymphocytes with low level of cellular atypia may be seen.