Ex vivo tissue modelling informs drug selection for rare cancers.

The identification and therapeutic targeting of actionable gene mutations across many cancer types has resulted in improved response rates in a minority of patients. The identification of actionable mutations is usually not sufficient to ensure complete nor durable responses, and in rare cancers, where no therapeutic standard of care exists, precision medicine indications are often based on pan-cancer data. The inclusion of functional data, however, can provide evidence of oncogene dependence and guide treatment selection based on tumour genetic data. We applied an ex vivo cancer explant modelling approach, that can be embedded in routine clinical care and allows for pathological review within 10 days of tissue collection. We now report that ex vivo tissue modelling provided accurate longitudinal response data in a patient with BRAFV600E -mutant papillary thyroid tumour with squamous differentiation. The ex vivo model guided treatment selection for this patient and confirmed treatment resistance when the patient's disease progressed after 8 months of treatment.

Comparing Genomic Landscapes of Oral and Cutaneous Squamous Cell Carcinoma of the Head and Neck: Quest for Novel Diagnostic Markers.

Squamous cell carcinoma is the most common head and neck malignancy arising from the oral mucosa and the skin. The histologic and immunohistochemical features of oral squamous cell carcinoma (OSCC) and head and neck cutaneous squamous cell carcinoma (HNcSCC) are similar, making it difficult to identify the primary site in cases of metastases. With the advent of immunotherapy, reliable distinction of OSCC and HNcSCC at metastatic sites has important treatment and prognostic implications. Here, we investigate and compare the genomic landscape of OSCC and HNcSCC to identify diagnostically useful biomarkers. Whole-genome sequencing data from 57 OSCC and 41 HNcSCC patients were obtained for tumor and matched normal samples. Tumor mutation burden (TMB), Catalogue of Somatic Mutations in Cancer (COSMIC) mutational signatures, frequent chromosomal alterations, somatic single nucleotide, and copy number variations were analyzed. The median TMB of 3.75 in primary OSCC was significantly lower (P < .001) than that of 147.51 mutations/Mb in primary HNcSCC. The COSMIC mutation signatures were significantly different (P < .001) between OSCC and HNcSCC. OSCC showed COSMIC single-base substitution (SBS) mutation signature 1 and AID/APOBEC activity-associated signature 2 and/or 13. All except 1 HNcSCC from hair-bearing scalp showed UV damage-associated COSMIC SBS mutation signature 7. Both OSCC and HNcSCC demonstrated a predominance of tumor suppressor gene mutations, predominantly TP53. The most frequently mutated oncogenes were PIK3CA and MUC4 in OSCC and HNcSCC, respectively. The metastases of OSCC and HNcSCC demonstrated TMB and COSMIC SBS mutation signatures similar to their primary counterparts. The combination of high TMB and UV signature in a metastatic keratinizing squamous cell carcinoma suggests HNcSCC as the primary site and may also facilitate decisions regarding immunotherapy. HNcSCC and OSCC show distinct genomic profiles despite histologic and immunohistochemical similarities. Their genomic characteristics may underlie differences in behavior and guide treatment decisions in recurrent and metastatic settings.

Whole genome duplication in oral squamous cell carcinoma in patients younger than 50 years: implications for prognosis and adverse clinicopathological factors.

INTRODUCTION: Oral squamous cell carcinoma (OSCC) in the young (<50 years), without known carcinogenic risk factors, is on the rise globally. Whole genome duplication (WGD) has been shown to occur at higher rates in cancers without an identifiable carcinogenic agent. We aimed to evaluate the prevalence of WGD in a cohort of OSCC patients under the age of 50 years. METHODS: Whole genome sequencing (WGS) was performed on 28 OSCC patients from the Sydney Head and Neck Cancer Institute (SHNCI) biobank. An additional nine cases were obtained from The Cancer Genome Atlas (TCGA). RESULTS: WGD was seen in 27 of 37 (73%) cases. Non-synonymous, somatic TP53 mutations occurred in 25 of 27 (93%) cases of WGD and were predicted to precede WGD in 21 (77%). WGD was significantly associated with larger tumor size (p = 0.01) and was frequent in patients with recurrences (87%, p = 0.36). Overall survival was significantly worse in those with WGD (p = 0.05). CONCLUSIONS: Our data, based on one of the largest WGS datasets of young patients with OSCC, demonstrates a high frequency of WGD and its association with adverse pathologic characteristics and clinical outcomes. TP53 mutations also preceded WGD, as has been described in other tumors without a clear mutagenic driver.

Effect of operative time on complications associated with free flap reconstruction of the head and neck.

OBJECTIVE: To evaluate whether prolonged operative time is negatively associated with post-operative complications and length of stay in patients undergoing microvascular free flap reconstruction for complex head and neck defects. METHODS: 342 consecutive patients undergoing microvascular reconstruction for head and neck defects between 2017-2019 at a single institution were evaluated. Operative outcomes and operative time were compared whilst controlling for patient and treatment related factors. RESULTS: Mean operative time was 551 min and length of stay was 16.2 days. An 11% increase in the risk of a post-operative complication was observed for every additional hour of operative time (OR 1.11, 95% CI 1.03-1.21, p = 0.011) after adjusting for patient and treatment factors. A cut-off of 9 h yielded a 92% increase in complications on either side of this (OR 1.92, 95% CI 1.18-3.13, p = 0.009). Increased operative time was also associated with increased length of stay and return to theatres, but not medical complications. CONCLUSION: Prolonged operative time is significantly associated with increased surgical complications, length of stay and return to theatres when performing microvascular reconstructive surgery for head and neck defects.

Recursive Partitioning to Determine Order of Significance of Regional Metastasis Characteristics in Head and Neck Cutaneous Squamous Cell Carcinoma.

BACKGROUND: The order of significance of clinicopathologic characteristics for the prognosis of patients with regional metastases from head and neck cutaneous squamous cell carcinoma (HNcSCC) is not well characterized. This study aimed to understand the impact of the known characteristics, including the presence of immunosuppression, number of deposits, largest deposit size, location and laterality of deposits, and presence of extranodal extension (ENE) on overall survival (OS) and disease-specific survival (DSS). METHODS: A retrospective study of 366 patients treated with curative intent for HNcSCC with regional metastatic disease was undertaken using recursive partitioning analysis (RPA). RESULTS: Using RPA modeling, the study determined that number of metastatic deposits carried the highest impact for both OS and DSS, followed by largest deposit size. The presence of ENE and immunosuppression was less significant. CONCLUSIONS: The results from this study provide new evidence for identifying and stratifying high-risk patients with metastatic HNcSCC. This information will be valuable in determining future HNcSCC staging systems.

Targeted ordering of investigations reduces costs of treatment for surgical inpatients.

BACKGROUND: Laboratory testing forms an important part of diagnostic investigation in modern medicine; however, the overuse of 'routine blood tests' can result in significant potential harm and financial cost to the patient and the healthcare system. In 2018, a new protocol targeting the ordering of investigations was implemented within the General Surgical Teams of Wollongong Hospital in New South Wales, an Australian tertiary referral hospital, to reduce the number of 'routine blood tests' as a quality improvement initiative. OBJECTIVE: To identify whether there was a reduction in the number of 'routine blood tests' and associated costs following implementation of the new protocol. METHODS: The protocol involved regular review of the laboratory investigations being ordered for the following day with a senior team member. The medical records of all patients admitted under the general surgery service at Wollongong Hospital were retrospectively reviewed over two 10-week periods in 2017 and 2018 (control and study, respectively). The casemix was categorized into Minor, Intermediate, Major or Unscored, depending on case complexity coding. RESULTS: A total of 838 patients were identified during the control period (2017) and 805 patients were identified during the study period (2018). Ten thousand and thirty tests were included in the control period, compared to 8610 over the study period, resulting in a 16% (or greater) reduction in 'routine blood tests' per patient, per day of admission and a 6% reduction in costs in the study group (P < 0.001). CONCLUSION: Targeted ordering of investigations with personalized education and feedback to junior staff during review of clinical status of each patient as a part of normal workflow can reduce inappropriate ordering of 'routine blood tests' and associated costs to the patient and the healthcare system.

Sentinel Node Biopsy in 105 High-Risk Cutaneous SCCs of the Head and Neck: Results of a Multicenter Prospective Study.

BACKGROUND: Regional nodal metastases from cutaneous squamous cell carcinoma (cSCC) is strongly associated with a poor prognosis, but these metastases are difficult to predict clinically. Sentinel node biopsy (SNB) has been used for a wide range of malignancies to assess for regional nodal metastasis, but is not widely used for cSCC. METHODS: Patients presenting with high-risk cSCC of the head and neck with clinically N0 necks were offered SNB at the time of primary cSCC excision or secondary wide local excision. Patients with positive sentinel nodes were offered completion lymph node dissection, and all the patients were followed up at regular intervals for up to 5 years. RESULTS: In this study, 105 lesions underwent SNB, and 10 sentinel nodes (9.5%) were positive. In an additional five patients, regional recurrence developed after a negative sentinel node, with a total subclinical nodal metastasis rate of 14.3%. Nodal metastases were significantly associated with reduced disease-specific survival. The significant predictors of metastasis were four or more high-risk features or tumors with a concurrent invasion deeper than 5 mm and PNI. CONCLUSION: For high-risk cSCC, SNB is a safe and feasible staging technique. The total number of high risk features and certain combinations of high-risk features predicted metastasis better than individual high-risk features.

The extent of extrathyroidal extension is a key determinant of prognosis in T4a papillary thyroid cancer.

BACKGROUND AND OBJECTIVES: In papillary thyroid cancer (PTC), the adverse prognostic impact of extrathyroidal extension (macro-ETE) invading the subcutaneous soft tissues, larynx, trachea, esophagus, or recurrent laryngeal nerve (T4a disease) is well established. We investigated whether the extent of macro-ETE, defined as "limited" with single structure involvement (lim-ETE) and "extensive" with multiple structures involved (ext-ETE), influences prognosis in T4a PTC. METHODS: A retrospective analysis of 610 patients with PTC identified 39 with T4a disease, including 26 with lim-ETE and 13 with ext-ETE. Univariate Cox regression was used to assess the relationship between the extent of macro-ETE and recurrence-free survival (RFS). RESULTS: Ext-ETE was associated with a five times increased risk of recurrence compared to lim-ETE (HR 5.0, P < .030), with or without adjustment for radioactive iodine administration and after adjustment for margin status (HR 4.7; P = .041). A low-risk subset of T4a disease comprising of patients aged less than 55 years with lim-ETE and clear margins accounted for one-third of the cohort and demonstrated an excellent 5-year RFS of 92%. CONCLUSIONS: The extent of macro-ETE appears to be an important determinant of prognosis in T4a PTC. A low-risk subset of T4a disease exists with an excellent prognosis.

Differences in LC3B expression and prognostic implications in oropharyngeal and oral cavity squamous cell carcinoma patients.

BACKGROUND: This study examined the prognostic significance of microtubule-associated protein light chain 3B (LC3B) expression in oropharyngeal and oral cavity squamous cell carcinoma (SCC). The prognostic significance of LC3B expression in relation to human papillomavirus (HPV) status in oropharyngeal SCC was also examined. METHODS: Tissue microarrays (TMAs) were constructed from formalin-fixed, paraffin-embedded oropharyngeal (n = 47) and oral cavity (n = 95) SCC tissue blocks from patients with long-term recurrence and overall survival data (median = 47 months). LC3B expression on tumour was assessed by immunohistochemistry and evaluated for associations with clinicopathological variables. LC3B expression was stratified into high and low expression cohorts using ROC curves with Manhattan distance minimisation, followed by Kaplan-Meier and multivariable survival analyses. Interaction terms between HPV status and LC3B expression in oropharyngeal SCC patients were also examined by joint-effects and stratified analyses. RESULTS: Kaplan-Meier survival and univariate analyses revealed that high LC3B expression was correlated with poor overall survival in oropharyngeal SCC patients (p = 0.007 and HR = 3.18, 95% CI 1.31-7.71, p = 0.01 respectively). High LC3B expression was also an independent prognostic factor for poor overall survival in oropharyngeal SCC patients (HR = 4.02, 95% CI 1.38-11.47, p = 0.011). In contrast, in oral cavity SCC, only disease-free survival remained statistically significant after univariate analysis (HR = 2.36, 95% CI 1.19-4.67, p = 0.014), although Kaplan-Meier survival analysis showed that high LC3B expression correlated with poor overall and disease-free survival (p = 0.046 and 0.011 respectively). Furthermore, oropharyngeal SCC patients with HPV-negative/high LC3B expression were correlated with poor overall survival in both joint-effects and stratified presentations (p = 0.024 and 0.032 respectively). CONCLUSIONS: High LC3B expression correlates with poor prognosis in oropharyngeal and oral cavity SCC, which highlights the importance of autophagy in these malignancies. High LC3B expression appears to be an independent prognostic marker for oropharyngeal SCC but not for oral cavity SCC patients. The difference in the prognostic significance of LC3B between oropharyngeal and oral cavity SCCs further supports the biological differences between these malignancies. The possibility that oropharyngeal SCC patients with negative HPV status and high LC3B expression were at particular risk of a poor outcome warrants further investigation in prospective studies with larger numbers.

Differences in survival outcome between oropharyngeal and oral cavity squamous cell carcinoma in relation to HPV status.

BACKGROUND: This study examined the prognostic significance of human papillomavirus (HPV) in patients with oropharyngeal and oral cavity squamous cell carcinoma (SCC). METHODS: Tissue microarrays were constructed from oropharyngeal and oral cavity SCC (n = 143). The presence of functional HPV in tumour was determined by combined assessments of p16 immunohistochemistry and HPV in situ hybridisation. RESULTS: Oropharyngeal SCC patients presented with more advanced disease in comparison with oral cavity SCC patients (P = 0.001). HPV is present in 60% and 61% of oropharyngeal and oral cavity SCC patients, respectively. HPV-positive oropharyngeal SCC patients with advanced TNM stages displayed better overall and disease-free survival outcomes than HPV-negative patients (P = 0.022 and 0.046, respectively). Such survival differences were not observed in oral cavity SCC. CONCLUSIONS: HPV is common in both oropharyngeal and oral cavity SCC and is associated with better survival outcome in oropharyngeal SCC but not in oral cavity SCC patients.

Perforator variability in the anterolateral thigh free flap: a systematic review.

OBJECTIVES: The use of free flaps greatly improves reconstruction options and quality of life for patients undergoing oncological resections. The anterolateral thigh (ALT) free flap is frequently used in the head and neck. The aim of this review was to provide a summary of published evidence assessing perforator anatomy of this flap. METHODS: A broad search was undertaken through the PubMed database using the terms "anterolateral thigh free flap" and "perforator". Search limits included English language and human subjects. Studies that examined more than or equal to ten patients were analysed. RESULTS: A total of 23 studies were identified, which included both clinical and cadaver studies. 1251 thighs were examined with the mean number of perforators ranging from 1.15 to 4.26. In the majority of cases, the descending branch of the lateral circumflex femoral artery was the dominant pedicle and took a musculocutaneous route. In some series, up to 5.4% of thighs were identified as having no cutaneous perforators. Venous data is limited with most studies reporting the presence of two concomitant veins of which the largest concomitant vein is selected for venous anastomoses. CONCLUSIONS AND FUTURE STUDIES: The ALT free flap is a reconstruction option in head and neck cancer. Adequate perforators for reconstruction are identified in the majority of cases. Increased anatomical perforator knowledge may lead to further uptake of ALT free flap reconstruction and improved intraoperative troubleshooting. Further studies investigating those patients with no perforators in the ALT may lead to improved clinical outcomes.

How age affects health-related-quality-of-life outcomes in maxillomandibular reconstructive surgery.

INTRODUCTION: Maxillomandibular reconstruction has various functional, aesthetic, and psychosocial effects that can decrease patients' health-related quality of life (HRQOL). The aim of this study was to compare HRQOL outcomes in older and younger patients undergoing maxillomandibular reconstruction. METHODS: A cross-sectional study of patients undergoing maxillomandibular reconstruction surgery between November 2008 and January 2021 was conducted. Participants completed the FACE-Q Head and Neck Cancer Module, M.D. Anderson Dysphagia Inventory (MDADI), and Speech Handicap Index (SHI). Results from these instruments were used to compare HRQOL outcomes in old (≥70 years) and young (<70 years) patients. RESULTS: Ninety-nine patients who underwent maxillomandibular reconstruction completed the instruments (response rate 50%), of which 33 (33%) were aged ≥70 years. Older age was associated with improved FACE-Q speaking (+11.3, P = 0.045), FACE-Q cancer worry (-9.97, P = 0.050), and SHI score (-16.6, P = 0.013). After adjusting for the effect of radiotherapy, age was associated with improved FACE-Q speaking (+16.8, P = 0.012), FACE-Q smiling distress (+12.6, P = 0.040), FACE-Q worry (-11.0, P = 0.032), and SHI scores (-18.4, P = 0.004). Older age was associated with an increased likelihood of postoperative complications (odds ratio (OR) = 2.9, P = 0.02) and medical complications (OR = 4.6, P = 0.012). CONCLUSION: In patients undergoing maxillomandibular reconstruction, older age (≥70 years) was associated with better HRQOL outcomes in domains relating to speech and cancer worry. In all other HRQOL outcomes, the two age groups performed similarly.

When should patients with T1N0 oral squamous cell carcinoma be considered for elective neck dissection?

AIMS: To identify adverse pathological features (APF) predicting nodal failure in clinically node negative T1 oral squamous cell carcinoma (OSCC). METHODOLOGY: This study evaluated patients with T1N0 (≤5 mm depth of invasion (DOI) and ≤2 cm diameter) oral cancers from a prospectively maintained database between 1988 and 2020. All patients underwent surgical excision of the primary lesion without neck dissection. Patients underwent three monthly clinical surveillance and salvage neck dissection was performed if nodal relapse was diagnosed. RESULTS: Overall, 141 patients were included. Nodal relapse was reported in 16/141 (11.3%) patients. Factors impacting regional recurrence-free survival were DOI ≥3 mm (HR: 2.4, P < 0.001), maximum tumour diameter ≥12 mm (HR: 1.1, P = 0.009), perineural invasion (PNI) (HR 7.5, P = 0.002) and poor differentiation (HR 5.3, P = 0.01). Rates of nodal relapse increased from 2% amongst patients with no APFs to 100% for those with four APFs. Patients with two or more APFs had significantly poorer 5-year regional recurrence-free survival (94.8% vs. 56.3%, P < 0.001). CONCLUSION: Patients with T1N0 OSCC with two or more APFs (DOI ≥3 mm, diameter ≥12 mm, PNI or poor differentiations) should be considered for elective neck dissection.

Prognostic and predictive biomarkers in head and neck cancer: something old, something new, something borrowed, something blue and a sixpence in your shoe.

A biomarker is a measurable indicator of biological or pathological processes or the response to an exposure or intervention and is used to guide management decisions. In head and neck pathology, biomarkers are assessed by histological criteria and immunohistochemical and molecular studies. Surgical resection remains the mainstay of management of many head and neck malignancies. Adjuvant radiotherapy and/or systemic therapy may be administered depending on the presence of adverse prognostic factors identified on histopathological or immunohistochemical examination. In this review, we outline the clinically relevant prognostic and predictive factors in head and neck malignancies including conventionally recognised factors such as tumour size, depth of invasion, lymphovascular and perineural invasion and margin status as well as novel evolving factors such as recurrent genetic rearrangements and assessment of immune checkpoints. Practical issues are discussed to assist with recognising and reporting of these factors. A summary of useful tools such as structured pathology report formats is also included to assist with comprehensive reporting of all clinically relevant parameters, minimise risk and improve workflow efficiencies.

Novel Sheep Model to Assess Critical-Sized Bone Regeneration with Periosteum for In Vivo Bioreactors.

Considerable research is being undertaken to develop novel biomaterials-based approaches for surgical reconstruction of bone defects. This extends to three-dimensional (3D) printed materials that provide stable, structural, and functional support in vivo. However, few preclinical models can simulate in vivo human biological conditions for clinically relevant testing. In this study we describe a novel ovine model that allows evaluation of in vivo osteogenesis via contact with bone and/or periosteum interfaced with printed polymer bioreactors loaded with biomaterial bone substitutes. The infraspinous scapular region of 14 Dorset cross sheep was exposed. Vascularized periosteum was elevated either attached to the infraspinatus muscle or separately. In both cases, the periosteum was supplied by the periosteal branch of the circumflex scapular vessels. In eight sheep, a 3D printed 4-chambered polyetheretherketone bioreactor was wrapped circumferentially in vascularized periosteum. In 6 sheep, 12 double-sided 3D printed 2-chambered polyetherketone bioreactors were secured to the underlying bone allowing direct contact with the bone on one side and periosteum on the other. Our model enabled simultaneous testing of up to 24 (12 double-sided) 10 × 10 × 5 mm bioreactors per scapula in the flat contact approach or a single 40 × 10 mm four-chambered bioreactor per scapula using the periosteal wrap. De novo bone growth was evaluated using histological and radiological analysis. Of importance, the experimental model was well tolerated by the animals and provides a versatile approach for comparing the osteogenic potential of cambium on the bone surface and elevated with periosteum. Furthermore, the periosteal flaps were sufficiently large for encasing bioreactors containing biomaterial bone substitutes for applications such as segmental mandibular reconstruction.

Outcomes of immediate dental implants in vascularised bone flaps for mandibular reconstruction.

BACKGROUND: The aim of this study is to assess the outcomes of immediate implant placement for dental rehabilitation following mandibular reconstruction with vascularised bone flaps in a single Australian tertiary cancer centre. METHODS: A retrospective analysis of patients who underwent immediate dental implant or delayed placement in vascularised bone flaps was performed. Primary outcome measures assessed included the number of implants placed, operative time, complication rates, time to radiotherapy initiation, dental rehabilitation rates and time to dental rehabilitation. RESULTS: In total, 187 dental implants were placed in 52 patients, of which 34 patients underwent immediate implant placement and 18 had delayed implant placement. There were no significant differences in the postoperative complication rate (32% immediate vs. 33% delayed, P = 0.89) or time to postoperative radiotherapy (median 42 days immediate vs. 47 days delayed, P = 0.24). Dental rehabilitation was achieved in 62% of the immediate cohort versus 78% of the delayed cohort. The time to be fitted with a dental prosthesis was significantly shorter in the immediate cohort (median 150 days immediate vs. 843 days delayed, P = 0.002). CONCLUSIONS: The placement of immediate dental implants at the time of primary reconstruction of the mandible is a safe procedure and facilitates timely dental rehabilitation.

Comparative analysis of pre-operative ultrasound and histopathology in small papillary thyroid carcinoma in the era of active surveillance.

BACKGROUND: Contemporary management of small papillary thyroid carcinomas (PTC) includes active surveillance (AS) as a number of these tumours are indolent. Overseas studies have reported AS in tumours up to 15 mm. This study aims to look at an Australian cohort of patients who have had surgery for non-incidental PTCs and analyse their pre-operative ultrasound and histopathology data to investigate potential issues that might arise in the era of AS. METHODS: Retrospective review of 82 patients who had surgical removal of PTCs ≤15 mm in diameter. Pre-operative ultrasound imaging was reviewed by an experienced sonologist and histopathology data was obtained from medical records. The AS risk stratification framework by Brito et al. was used to determine those who were feasible for AS based on ultrasound findings. RESULTS: Review of pre-operative ultrasounds demonstrated there were 68 (82.9%) patients who were shown to be either appropriate or ideal for AS. On review of histopathology, 49 (69%) patients had at least one adverse pathological risk factor. This is more than half of the patients that were originally identified as candidates for AS. CONCLUSION: Our study has revealed a large proportion were suitable for AS but when compared with histopathological guidelines there was a high incidence of adverse pathological features found. This discrepancy indicates that although the guidelines are important, there are unknown pathological variables that need to be considered in patients selected for AS.

Persisting facial nerve palsy or trigeminal neuralgia - red flags for perineural spread of head and neck cutaneous squamous cell carcinoma (HNcSCC).

BACKGROUND: Perineural spread (PNS) of head and neck cutaneous squamous cell carcinoma (HNcSCC) is a unique diagnostic challenge, presenting with insidious trigeminal (CN V) or facial nerve (CN VII) neuropathies without clinically discernible primary masses. These patients are often sub-optimally investigated and misdiagnosed as Bell's palsy or trigeminal neuralgia. This case series highlights the red flags in history and pitfalls that lead to delays to diagnosis and treatment. METHODS: A retrospective case series of 19 consecutive patients with complete clinical histories with HNcSCC PNS without an obvious cutaneous primary lesion at time of presentation to a quaternary head and neck centre in Australia were identified and included for analysis. RESULTS: Fifteen had CN VII PNS, 17 had CN V PNS, and 13 had both. The overall median symptom-to-diagnosis time was 12-months (IQR-15 months). Eight patients had CN VII PNS and described progressive segmental facial nerve palsy with a median symptom-to-diagnosis time of 9-months (IQR-11.75 months). Eleven patients had primary CN V PNS and described well localized parathesia, formication or neuralgia with a median symptom-to-diagnosis time of 19-months (IQR 27.5 months). CONCLUSION: PNS is often mistaken for benign cranial nerve dysfunction with delays in diagnosis worsening prognosis. Red flags such as progressive CN VII palsy or persistent CN V paraesthesia, numbness, formication or pain, particularly in the presence of immuno-compromise and/or a history of facial actinopathy should raise suspicion for PNS. Gadolinium-enhanced MR Neurography should be obtained expediently in patients with persistent/progressive CN V/CN VII palsies in patients with red flags, with low threshold for referral to a Head and Neck Surgeon.