Accuracy in the diagnosis of parotid tumours

Use of the SMAS flap for reconstruction of the parotid lodge

The purpose of our study was to evaluate the benefits of the SMAS flap in patients with benign tumours of the parotid gland treated by superficial parotidectomy. We carried out a retrospective chart review on 123 patients suffering from benign tumours of the parotid gland admitted to our Institution between March 1997 and March 2010. A superficial parotidectomy was performed in all the cases reported. Our sample was divided in two groups basing SMAS flap reconstruction done (Group 2) or not (Group 1) after superficial parotidectomy. Reconstruction using SMAS flap was accomplished in 64 patients. Chi-square test was used to assess statistical difference between the two groups. The level of statistical significance was P < 0.05. No significant differences concerning hematoma, wound infection and facial paralysis were observed between the first and second group (3.38 vs 1.56% [P > 0.05], 8.47% vs 4.68% [P > 0.05], 5.08% vs 0.00% [P > 0.05]). Transient facial nerve weakness, fistula, dip skin and Frey's syndrome were significantly more frequent without SMAS flap reconstruction (10.16% vs 3.125% [P < 0.05], 13.55% vs 3.125% [P < 0.05], 13.55% vs 3.125% [P < 0.05], 20.33% vs 0% [P < 0.05] respectively). The use of the SMAS flap is able to reduce the cosmetic and functional complications that occur after the removal of a benign tumour of the parotid through the superficial parotidectomy technique, above all, it reduces the occurrence of Frey's syndrome.

Sensitivity, Specificity, and Posttest Probability of Parotid Fine-Needle Aspiration: A Systematic Review and Meta-analysis

OBJECTIVES

(1) To analyze the sensitivity and specificity of fine-needle aspiration (FNA) in distinguishing benign from malignant parotid disease. (2) To determine the anticipated posttest probability of malignancy and probability of nondiagnostic and indeterminate cytology with parotid FNA.

DATA SOURCES

Independently corroborated computerized searches of PubMed, Embase, and Cochrane Central Register were performed. These were supplemented with manual searches and input from content experts.

REVIEW METHODS

Inclusion/exclusion criteria specified diagnosis of parotid mass, intervention with both FNA and surgical excision, and enumeration of both cytologic and surgical histopathologic results. The primary outcomes were sensitivity, specificity, and posttest probability of malignancy. Heterogeneity was evaluated with the I(2) statistic. Meta-analysis was performed via a 2-level mixed logistic regression model. Bayesian nomograms were plotted via pooled likelihood ratios.

RESULTS

The systematic review yielded 70 criterion-meeting studies, 63 of which contained data that allowed for computation of numerical outcomes (n = 5647 patients; level 2a) and consideration of meta-analysis. Subgroup analyses were performed in studies that were prospective, involved consecutive patients, described the FNA technique utilized, and used ultrasound guidance. The I(2) point estimate was >70% for all analyses, except within prospectively obtained and ultrasound-guided results. Among the prospective subgroup, the pooled analysis demonstrated a sensitivity of 0.882 (95% confidence interval [95% CI], 0.509-0.982) and a specificity of 0.995 (95% CI, 0.960-0.999). The probabilities of nondiagnostic and indeterminate cytology were 0.053 (95% CI, 0.030-0.075) and 0.147 (95% CI, 0.106-0.188), respectively.

CONCLUSION

FNA has moderate sensitivity and high specificity in differentiating malignant from benign parotid lesions. Considerable heterogeneity is present among studies.

Verification bias in diagnostic accuracy studies for fine- and core needle biopsy of salivary gland lesions in otolaryngology journals: a systematic review and analysis

BACKGROUND

Diagnostic test accuracy (DTA) studies for needle biopsy are frequently published in otolaryngology journals, but this body of literature has not been assessed for verification bias.

METHODS

We conducted a systematic review of DTA studies on needle biopsy of salivary gland lesions appearing in otolaryngology journals. Studies were assessed by 2 reviewers for verification bias.

RESULTS

We identified 95 DTA studies for needle biopsy of salivary gland lesions. Eighty-one studies (84%) had verification bias. Five of the biased studies provided sufficient data to estimate the extent of bias. Verification bias was associated with an overestimate of sensitivity and an underestimate of specificity. Studies on core needle biopsy (CNB) had a lower rate of verification bias than fine-needle aspiration (FNA) studies.

CONCLUSION

Verification bias is common in DTA studies of needle biopsy for salivary gland lesions published in ear, nose, and throat (ENT) journals. Such studies overestimated sensitivity and underestimated specificity.

A systematic review and meta-analysis of the diagnostic accuracy of fine-needle aspiration cytology for parotid gland lesions

The clinical usefulness of fine-needle aspiration cytology (FNAC) for the diagnosis of parotid gland lesions is controversial. Many accuracy studies have been published, but the literature has not been adequately summarized. We identified 64 studies on the diagnosis of malignancy (6,169 cases) and 7 studies on the diagnosis of neoplasia (795 cases). The diagnosis of neoplasia (area under the summary receiver operating characteristic [AUSROC] curve, 0.99; 95% confidence interval [CI], 0.97-1.00) had higher accuracy than the diagnosis of malignancy (AUSROC, 0.96; 95% CI, 0.94-0.97). Several sources of bias were identified that could affect study estimates. Studies on the diagnosis of malignancy showed significant heterogeneity (P < .001). The subgroups of American, French, and Turkish studies showed greater homogeneity, but the accuracy of these subgroups was not significantly different from that of the remaining subgroup. It is not possible to provide a general guideline on the clinical usefulness of FNAC for parotid gland lesions owing to the variability in study results. There is a need to improve the quality of reporting and to improve study designs to remove or assess the impact of bias.

Synchronous ipsilateral Warthin tumor encased by a separate mucoepidermoid carcinoma of the parotid gland: a case report and review of the literature

Fine-needle aspiration (FNA) is a cost effective and low morbidity procedure in the initial assessment of salivary gland tumors. However, cytological assessment of ipsilateral synchronous tumors (which make up less than 0.3% of all salivary gland neoplasms) may pose diagnostic challenges. Therefore, a wholesome approach, including FNA with clinical and radiological correlation, is of utmost importance. Here, we report a unique case of Warthin tumor encased by a separate high-grade mucoepidermoid carcinoma that was first diagnosed on FNA. Another striking feature seen was the presence of chronic sialadenitis in the surrounding nonneoplastic salivary gland. The presence of two different neoplasms in the background of chronic sialadenitis raises the question of a possible causal relationship. Traditionally, there has been diagnostic difficulty when dealing with synchronous tumors of the salivary gland and the background of chronic sialadenitis may further complicate the diagnosis. FNA is very helpful and can give important cues to the diagnosis.

Validade da punção biópsia por agulha fina nas doenças da glândula parótida

OBJETIVO: Avaliar o método de punção biópsia aspirativa por agulha fina (PBAAF), técnica relativamente simples, de conhecida importância em cirurgia de cabeça e pescoço. Sua indicação em doenças das glândulas salivares, no entanto, especialmente na parótida, ainda é muito controversa na literatura. O diagnóstico pela PBAAF permite o adequado planejamento terapêutico e preparo do paciente. Muitos, porém, alegam que seu emprego acrescenta muito pouco à conduta terapêutica, além de ser procedimento doloroso e elevar o custo do tratamento. MÉTODO: Os autores analisaram os prontuários de 247 pacientes submetidos a parotidectomias, realizadas entre 1986 e 1998, comparando a punção aspirativa por agulha fina com o anatomopatológico definitivo. Isso foi possível em 211 casos. Houve predomínio do sexo feminino, com idade variando de dez a 84 anos. RESULTADOS: Os tumores benignos foram os mais prevalentes, correspondendo a 85,3% dos casos, com predomínio do adenoma pleomórfico. A punção por agulha fina permitiu diferenciar tumores benignos de malignos em 165 casos (78,1%) e acertou o diagnóstico histológico em 77,6 %. CONCLUSÕES: Concluímos que a PBAAF é um método eficiente e simples que fornece ao cirurgião diagnóstico das neoplasias na grande maioria das vezes e deve fazer parte, sempre que possível, da documentação pré-operatória.

Accuracy of fine needle aspiration biopsy in head and neck tumors

PURPOSE

Fine-needle aspiration biopsy (FNAB) is frequently used in the diagnosis of lesions occurring in the head and neck region. This study evaluated the correlation between the findings on FNAB and the histological findings observed after surgery.

MATERIALS AND METHODS

A review of 218 patients who underwent FNAB of a head or neck tumor was performed. Cytological reports were classified into the following diagnostic categories: negative or positive for malignant cells and unsatisfactory. False-positive, false-negative, true-positive (sensitivity), and true-negative (specificity) rates were calculated.

RESULTS

Twelve specimens did not allow an adequate diagnosis (5.5%). Among benign tumors, 96.2% of the cases were correctly diagnosed, and 3.8% were nondiagnostic specimens. Among malignant tumors, 86.4% of cases were correctly identified. There were two (3.4%) false-negatives and six (10.2%) nondiagnostic specimens, with a total false-negative rate of 13.6%.

CONCLUSIONS

Sampling errors present a minor problem with FNAB. Most nondiagnostic or incorrect specimens were caused by nonhomogenous lesions, with poor placement of the needle and an insufficient amount of aspirated material. FNAB is a useful modality for the diagnosis of head and neck masses.

Sources of diagnostic error in the fine-needle aspiration diagnosis of Warthin's tumor and clues to a correct diagnosis

Squamous metaplasia and cystic degeneration in Warthin's tumor (WT) are not uncommon. A recent case of WT misdiagnosed as metastatic squamous carcinoma with cystic change prompted us to review our experience with fine-needle aspiration (FNA) of WT, with special attention given to potential sources of diagnostic pitfalls. Aspirations from 16 cases of histologically confirmed WT were retrospectively evaluated for cellularity, cell composition, and background. The FNA review diagnosis was compared with the previous FNA and corresponding tissue findings. All tumors presented in the parotid gland. The initial cytologic diagnoses were: WT in 13 cases, oncocytoma vs. low-grade mucoepidermoid carcinoma in 1, squamous carcinoma vs. branchial cleft cyst in 1, and squamous carcinoma in 1. On review, 13 cases (81%) showed typical features associated with WT: Moderate to abundant oncocytic epithelium, lymphoid stroma, background debris, and mild squamous metaplasia. In the remaining cases, one lacked a lymphoid stroma and could not be further classified (initially called "oncocytoma vs. low-grade mucoepidermoid carcinoma"). The other 2 cases contained moderate to abundant atypical squamous cells and extensive necrotic/mucoid debris, and review diagnoses were consistent with the initial cytologic diagnoses (squamous carcinoma in one, and branchial cleft cyst vs. squamous carcinoma in the other). In our series, typical features of WT were seen in 81% of cases. Atypical features are largely present as individual metaplastic squamous cells. Diagnostic errors are caused by a lack of typical features and the presence of individual atypical squamous cells in a necrotic background mimicking carcinoma. An awareness of the morphologic variation present on cytologic preparations and correlation with clinical findings should prevent erroneous interpretation in the FNA setting.

Fine-needle aspiration biopsy of parotid lesions: comparison with frozen section

BACKGROUND

Opinions vary as to the necessity for fine-needle aspiration biopsy (FNAB) in parotid tumours. The present study reflects the experience gained over a 12-year period and shows the accuracy of a diagnostic FNAB, and improved results with experience.

METHODS

Between 1983 and 1995, 201 parotid lesions were excised by one surgeon(AGP) and a prospective database was established. Fine-needle aspiration biopsy was performed prior to surgery in 195 lesions and frozen section was performed in 159 lesions.

RESULTS

The FNAB was diagnostic in 129 (66%) specimens and its sensitivity for malignancy was 90% and specificity was 100% (excluding non-diagnostic FNAB, where there was insufficient cellular material for reliable diagnosis or where specific tissue diagnosis could not be given). The positive predictive value was 100% and the negative predictive value was 98%. Of interest, the positive predictive value of diagnostic FNAB for pleomorphic adenomas was 99%. A specific tumour diagnosis could not be made on the FNAB sample in 37 specimens; 11 of these lesions were histologically confirmed as malignant after excision. Frozen section was diagnostic in 144 specimens (91%). Its sensitivity for malignancy was 96% and specificity was 99%. The positive predictive value was 96% and negative predictive value 99%. A specific tumour diagnosis could not be made on frozen section in 15 specimens including six cases in which malignancy was finally reported. The positive predictive value of diagnostic frozen section for pleomorphic adenomas was 99%.

CONCLUSIONS

A diagnostic FNAB is an accurate and useful tool in the management of parotid lesions. An FNAB diagnosis of pleomorphic adenoma obviates the need for frozen section. The performance of FNAB in parotid tumours does not in any way preclude the necessity of surgical removal of such lesions except in exceptional circumstances.