Spindle cell carcinoma of the larynx: review of 26 cases including DNA content and immunohistochemistry.

Spindle cell carcinoma (SpCC) is uncommon, with a predilection for the upper aerodigestive tract. Its histogenesis has not been resolved, although most authors support the sarcomatoid carcinoma concept. Ploidy analysis and proliferation indices have not been reported for laryngeal SpCCs. The authors examined the pathological and clinical features of 26 patients (25 men, 1 woman; mean age, 64 years) with laryngeal SpCC treated at the Mayo Clinic from 1960 to 1990. Twenty-three tumors were examined with digital image analysis for DNA content of the spindle cell population (13 tumors had a sufficient squamous component to be analyzed separately). The glottis was involved most frequently (19 patients); 21 tumors were grossly polypoid. Twenty-three tumors were biphasic, and three were monophasic. Overall, 17 tumors (65%) showed keratin positivity in the spindle cell component. Polyclonal antikeratin (15 positive cases), 34betaE12 (15 positive), and AE1/AE3 (12 positive) were the most sensitive markers. Spindle cells were diploid in 5 tumors (22%) and nondiploid in 18 (78%); conventional squamous cell carcinoma was diploid in 4 cases and nondiploid in 9. DNA ploidy results were concordant between the two populations in 11 of 13 tumors (85%). Mean percent MIB-1 staining was 31% in the sarcomatoid component and 45% in the squamous component. In our primary treatment group of 22 patients (median follow-up, 6.4 years), 4 (18%) had local recurrence, 3 (14%) had distant metastasis, and 4 (18%) died of disease. Presence of a nondiploid spindle cell population in 78% of cases of laryngeal SpCC is interpreted as evidence of a neoplastic rather than reactive process. Keratin positivity in nearly two thirds of tumors supports the theory of epithelial origin of these tumors (sarcomatoid carcinoma).