Pulmonary tumorlets with surrounding fibrous tissue--suspected carcinoma: case report and review of the literature.

Pulmonary tumorlets are small, often multiple nodular proliferations of pulmonary neuroendocrine cells. They are common incidental findings in chronic inflammatory pulmonary diseases. They can also be found in normal lung parenchyma and as one part of the continuum known as diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. In many cases, they are incidental histologic findings of no importance or clinical consequences, or they can be associated with a very slow progression of either obstructive or mixed obstructive/restrictive impairment with good prognosis. Only rarely, they metastasize to an adjacent lymph node or produce ectopic neuroendocrine products. When found during diagnostic examination, they represent a doubt to be a malignant tumor until proven otherwise, which is often impossible without biopsy or surgical removal of the adjacent lung lobe. Hereby, we present a patient with a persistent nodular lung structure after being treated for nonspecific symptoms, cough with non purulent sputum and pain among the scapulae, for a period of one month. He had otherwise normal clinical and laboratory findings, except for a mild mixed obstructive/restrictive pattern of impairment that was shown by lung spirometry. After 8 months, he underwent lobectomy of the medial lobe of the lung with partial lymphadenectomy, since the diagnostic methods applied could not define the nature of lung nodular infiltration. Histologic examination showed a few tumorlets surrounded by the fibrous tissue with a very dense lymphocyte infiltration. We present a review of the literature and emphasize the necessity to include tumorlets with adjacent fibrosis as part of the differential diagnosis of a solitary nodular lung structure.