Malignant salivary gland tumours of the larynx: a single institution review.

Malignant salivary gland tumours of the larynx are very rare, with limited reports of clinical outcomes. We present the decade-long experience of a single institution. A 10-year retrospective chart review of a tertiary head and neck cancer centre was performed. Index patients were identified from a review of a pathology database, and reviewed by a head and neck pathologist. Patient demographics, presenting signs and symptoms, treatment modalities and clinical outcomes were extracted from electronic medical records. Six patients were included, with an age range of 44 to 69. All six had malignant laryngeal salivary gland tumours. Pathologies included: three adenoid cystic carcinoma (2 supraglottic, 1 subglottic), one mucoepidermoid carcinoma (supraglottic), one epithelial-myoepithelial carcinoma (supraglottic) and one adenocarcinoma (transglottic). All were treated with surgery (2 endolaryngeal, 4 open) and five of six with the addition of adjuvant therapy (4 radiotherapy, 1 concurrent chemoradiation). One patient had smoking history; no patients had significant alcohol history. With 4.5 years of median follow-up, none of the patients has had recurrence or local/distant metastasis. Salivary gland tumours of the larynx present in mid to late-age, and can be successfully managed with a multi-modality approach, resulting in excellent local and regional control rates.

Non-epithelial tumors of the larynx: a single institution review.

AIM: Non-epithelial tumors of the larynx are rare and encompass a wide range of pathology. We present the decade-long experience of a single institution to define clinical presentations and outcomes. MATERIAL AND METHODS: This is a ten year retrospective chart review of a tertiary head and neck cancer center. Index patients were identified from a review of a pathology database, and patient demographics, presenting signs and symptoms, treatment modalities, and clinical outcomes were extracted from electronic medical records. Epithelial tumors (squamous cell carcinoma, spindle cell carcinoma, and salivary tumors), granulomas, sarcoidosis, papilloma, and amyloidosis were all excluded. RESULTS: Twenty-four patients with ages ranging from 2months-old to 84years were identified. Malignant lesions (11) included chondrosarcoma (6), Kaposi's sarcoma (2), metastatic melanoma, synovial cell sarcoma, and T cell neoplasm. Six were operated upon endolaryngeally, but four required either upfront or salvage total laryngectomy. Two received adjuvant therapy. Benign lesions (13) included hemangioma (4), granular cell tumor (3), myofibroblastic tumor (2), schwannoma (2), chondroma, and ossifying fibromyxoid tumor. Nine underwent endolaryngeal operations, and four were managed medically or with observation. None have required aggressive open resection or total laryngectomy. CONCLUSION: Treatment approach of non-epithelial tumors of the larynx depends on the site and extent of the tumor, histology, and sensitivity of adjuvant therapy. Benign tumors can be managed without need for aggressive resection thereby sparing laryngeal function.

Effect of isopropyl-beta-D-thiogalactopyranosid induction of the lac operon on the specificity of spontaneous and doxorubicin-induced mutations in Escherichia coli.

Previous studies of doxorubicin-induced mutations employing F' lacl/lacO as an endogenous gene target have focused on properties of large deletions with 3' endpoints residing in the lacO region of the target gene. This study considers the influence of Lac repressor binding on the distribution of these deletions. Results of the DNA sequence level analysis of spontaneous and doxorubicin-induced i-d and lacO mutations in Escherichia coli uvrB- are reported for mutants isolated under conditions where Lac repression is relieved by isopropyl-beta-D-thiogalactopyranosid (IPTG; an inducer that prevents repressor binding to lacO). The location of deletions isolated from doxorubicin-treated cultures in the presence and absence of IPTG suggests that doxorubicin preferentially focuses deletion endpoints adjacent to its binding sites in lacO and that the distribution of these deletion endpoints is not modulated by Lac repressor binding. In contrast, spontaneous deletion endpoints are preferentially clustered in the loop away from the palindromic sequences under conditions of repression. However, when the Lac repressor/lacO binding complex is dissociated by IPTG, the spontaneous 3'-deletion endpoints distribute proportionally between the putative stem and loop of the lacO palindrome. The single most striking effect of IPTG induction of the Lac operon was elimination of a "hot spot" for T:A-->C:G transitions at position +6 in lacO. This base substitution "hot spot," which accounted for 17.6% of total doxorubicin-induced mutants and 16.4% of spontaneous mutants in repressed bacterial cultures, accounted for approximately 1% of total mutations in similar experiments carried out in the presence of IPTG. A large number of mutations at the +6 position are induced only by doxorubicin in the absence of IPTG, however, suggesting that both doxorubicin-induced and spontaneous mutation at this transition "hot spot" are mediated by Lac repressor binding to lacO.