Contributed by Sanja Dacic, MD and Prabha B. Rajan, MDFINAL DIAGNOSIS:
ATYPICAL CARCINOID TUMOR WITH ANGIOLYMPHATIC INVASION AND METASTASIS IN TWO OF FOUR HILAR LYMPH NODES.
DISCUSSION
The bronchial carcinoids occur approximately equally in men and women. The peak incidence is in the fifth decade of life, although they may occur from the first to ninth decades of life. The atypical carcinoid tumors, however, reach their peak incidence approximately a decade later. Despite the presence of hormonal products within the neurosecretory granules in the cells, most bronchial carcinoids initially cause local manifestations rather than systemic manifestations. Only 1% of cases of Cushing's syndrome is caused by ectopic production of corticotropin or corticotropin releasing hormone (1, 2).
It is difficult to distinguish clinically Cushing's syndrome induced by bronchial carcinoid from that induced by pituitary adenoma. Bronchial carcinoid hormone secretion can be suppressed by high dose prednisone or metyrapone, thereby mimicking pituitary Cushing's syndrome (3). The classic tests used to differentiate central from ectopic hypercortisolism are relatively unhelpful. Previous studies suggest that ACTH-producing carcinoid tumors are more aggressive than hormonally quiescent typical carcinoids. However, survival depends on the grade and stage of the tumor. In general, localized typical carcinoid without lymph node metastases is associated with a 5-year-survival of 94%; if the lymph nodes are involved, the 5-year-survival is reduced to 71%. However, the 5-year-survival of patients with atypical bronchial carcinoids is only 57% (1).
According to Shrager (2), 57% of the ACTH producing carcinoid tumors demonstrate either lymphatic or vascular invasion. These findings suggest that ACTH producing carcinoids, although not meeting standard criteria for atypical carcinoids, appear to have a lower mortality rate than non-secretory atypical carcinoids, but demonstrate more malignant characteristics. They have an intermediate behavior between hormonally inactive typical and atypical carcinoids. According to Shrager these tumors should be labeled as Kultschitzsky cell carcinoma type IIb (2,4). These tumors have metastatic potential similar to the atypical carcinoid or well differentiated neuroendocrine carcinoma (5), but without the same ramifications for survival. These tumors are usually typical carcinoids by standard histologic criteria, but they have a greater metastatic potential, so they resemble atypical carcinoid tumors in this regard. Treatment of this tumor is the same as that of more aggressive malignant tumors, that is surgical resection and mediastinal lymph node dissection. This approach may have a high cure rate.
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Contributed by Sanja Dacic, MD and Prabha B. Rajan, MD
