Diffusion-weighted echo-planar MR imaging of primary parotid gland tumors: is a prediction of different histologic subtypes possible?

BACKGROUND AND PURPOSE: Our aim was to determine the value of echo-planar diffusion-weighted MR imaging (epiDWI) in differentiating various types of primary parotid gland tumors. MATERIALS AND METHODS: One hundred forty-nine consecutive patients with suspected tumors of the parotid gland were examined with an epiDWI sequence by using a 1.5T unit. Image analysis was performed by 2 radiologists independently, and the intraclass correlation coefficient was computed. Histologic diagnosis was obtained in every patient. For comparison of apparent diffusion coefficients (ADCs), a paired 2-tailed Student t test with a Bonferroni correction was used. RESULTS: In 136 patients, a primary parotid gland tumor was confirmed by histology. Among the observers, a high correlation was calculated (0.98). ADC values of pleomorphic adenomas were significantly higher than those of all other entities, except for myoepithelial adenomas (P = .054). ADC values of Warthin tumors were different from those of myoepithelial adenomas, lipomas, and salivary duct carcinomas (P < .001, 0.013, and .037, respectively). Mucoepidermoid carcinomas, acinic cell carcinomas, and basal cell adenocarcinomas were not differentiable from Warthin tumors (P = .094, .396, and .604, respectively). CONCLUSION: epiDWI has the potential to differentiate pleomorphic adenoma and myoepithelial adenomas from all other examined entities. Due to an overlap not only within the group of benign and malignant lesions but also between groups, diagnoses should not be addressed on the basis of ADC values solely. Therefore, further studies combining DWI, morphologic criteria, and probably other MR imaging techniques seem warranted.

Nasal glioma presenting as capillary haemangioma.

UNLABELLED: We report the case of a 5-month-old female infant with a congenital nasal tumour originally attributed to a capillary haemangioma. Doppler-flow ultrasound imaging revealed a solid mass surrounded by mildly enlarged vessels which had a flow pattern atypical of haemangioma. Histology showed non-malignant gliomatous cells with low proliferative activity. A diagnosis of nasal glioma was thus established and the patient underwent cranial MRT which excluded intracranial communication of the nasal glioma. Nasal gliomas arise from a skull defect, originating from the defective closure of the anterior neuroporus. They represent encephaloceles which have lost their intracranial connection. Nasal gliomas usually present shortly after birth as an intranasal obstruction or, as in our case, as a mostly extranasal tumour. CONCLUSION: Nasal glioma is often misdiagnosed as a capillary haemangioma. It can be distinguished from the latter by Doppler-flow ultrasonography. Magnetic resonance imaging is required to exclude intracranial communication.

[Histogenesis and development of membranous basal cell adenoma of the salivary gland].

OBJECTIVE: To investigate the histogenesis and development of membranous basal cell adenoma in the salivary glands. METHODS: A histological and immunohistochemical study was carried out on 12 cases of membranous basal cell adenoma in the salivary glands. RESULTS: In 4 cases, multiple focal proliferations of striated ducts in the surrounding salivary gland were conspicuous, which allowed tracing the development of the tumors from their origin. The earliest changes were characterized by hyperplasia of the basal cells of striated ducts. Continuous ductal proliferation lead to the formation of microadenomas. CONCLUSIONS: Proliferation of basal cells of the striated ducts apparently participate in, and play a main role in the histogenesis of some membranous basal cell adenomas of the salivary glands.

[A clinicopathologic study on membranous basal cell adenoma].

OBJECTIVE: To investigate the clinicopathologic features and behaviour of membranous basal cell adenoma. METHODS: Twelve cases with membranous basal cell adenoma of salivary gland were analysed clinicopathologically. RESULTS: The tumors were composed of epithelial islands of various sizes and shapes. Its histologic finding was characterized by palisading of peripheral cells and excessive hyaline basal membrane. Four cases had co-existing dermal cylindromas of the scalp. In 8 cases, the tumors demonstrated multiple origin. One case showed malignant transformation and cervical lymph node metastasis. CONCLUSIONS: The differential diagnosis involved the solid variant of basal cell adenoma, basal cell adenocarcinoma, solid subtype of adenoid cystic carcinoma and basal squamous cell carcinoma. Total parotidectomy rather than superficial parotidectomy is suggested to avoid the recurrence of the tumor. A close follow up after treatment is necessary.

Histogenesis and development of membranous basal cell adenoma.

The histogenesis of salivary gland tumors remains controversial. A histologic and immunohistochemical study was carried out on 12 cases of membranous basal cell adenoma in the salivary glands to investigate its histogenesis and development. In 4 cases, multiple focal proliferations of striated ducts in the surrounding salivary gland, which were conspicuous, allowed tracing of the development of the tumors from their origin. The earliest changes were characterized by hyperplasia of the basal cells of striated ducts. Continuous ductal proliferation led to the formation of microadenomas. The observations suggest that proliferating basal cells of striated ducts apparently participate in and play a main role in the histogenesis of some membranous basal cell adenomas of the salivary glands.