S-100 PROTEIN-POSITIVE (SUSTENTACULAR) CELLS IN PULMONARY CARCINOID TUMORLETS - A QUANTITATIVE STUDY OF 24 CASES

Stellate-shaped S-100 protein positive sustentacular cells (SCs) appea r to correlate inversely with the degree of tumor malignancy in some n euroendocrine tumors. Therefore, the SCs have been investigated in car cinoid pulmonary tumorlets and subsequently examined quantitatively in order to provide a basis for estimation of this phenomenon in tumorle t related lesions, especially carcinoids and neuroendocrine carcinomas . Pulmonary tissue from twenty-four patients with carcinoid tumorlets was studied immunochistochemically for S-100 protein positive SCs toge ther with glial fibrillary acidic protein, actin, desmin, vimentin and cytokeratins. Tumorlets SCs were calculated per 10,000 tumorlet eleme nts. The presence of SCs was proven in 18 subjects (75%) of all examin ed cases with quantitative frequency between 13 and 196 SCs per 10,000 tumorlet elements. The histogram showed three separate clusters of ca ses. Cluster 2 and cluster 3 with strikingly high frequency of SCs, i. e. from 66 up to 196 SCs per 10,000 tumorlet cells, may represent the biphasic differentiation potential of tumorlet elements. The mentioned lesions could be regarded as the possible precursors of pulmonary par agangliomas or paraganglioid carcinoids.