Intracranial solitary fibrous tumor/hemangiopericytoma: tumor reclassification and assessment of treatment outcome via the 2016 WHO classification.

PURPOSE: As per the 2016 World Health Organization (WHO) guidelines on the classification of central nervous system tumors, solitary fibrous tumors (SFTs) and hemangiopericytomas (HPCs) constitute a single disease entity, known as SFT/HPC. This study provides a clinical analysis of these tumors and describes the treatment outcomes of SFT/HPCs. METHODS: This retrospective study included 76 patients with histopathologically proven SFT/HPC. Reclassification according to the 2016 WHO guideline was done for patients who were diagnosed with SFT or HPC based on the 2007 WHO classification. Recurrence-free survival (RFS) and overall survival (OS) were evaluated for all patients and subgroups. RESULTS: The median follow-up period was 77.9 months. The median RFS and OS were 126.5 and 136.8 months, respectively. The 1-, 5-, 10-, and 15-year RFS rates were 93%, 72%, 40%, and 40%, respectively. The 1-, 5-, 10- and 15-year OS rates were 97%, 89%, 54%, and 35%, respectively. In multivariable analyses, stereotactic radiosurgery (SRS; p = 0.009, hazard ratio [HR] 6.986), female sex (p = 0.023, HR 1.76), and age over 45 (p = 0.037, HR 2.74) were associated with shorter RFS. Patients who underwent SRS as initial treatment had a shorter OS than that of patients who underwent primary resection (p < 0.001, HR 12.86). CONCLUSIONS: High-grade tumors tended to have worse OS and occur extracranial metastases earlier than low-grade tumors. The median RFS was not different between grade II and III tumors. Male sex, younger age, and GTR were associated with a better RFS. A history of SRS before tumor resection was associated with a shorter RFS and OS.

Anaplastic Hemangiopericytoma of the Jugular Foramen: Case Report and Systematic Review.

BACKGROUND: Hemangiopericytomas (HPCs) and solitary fibrous tumors (SFTs) are rare tumors of mesenchymal origin. Here, the authors present a rare case of anaplastic HPC in the jugular foramen (JF). The authors also conduct a systematic review of the literature to examine the current fund of knowledge on JF HPC/SFTs. METHODS: A systematic MEDLINE search was conducted using key words "hemangiopericytoma" OR "solitary fibrous tumor" AND "jugular foramen" OR "extracranial" OR "skull base." Clinicopathologic characteristics and outcomes of the present case were reviewed and compared with those in the literature. RESULTS: A 41-year-old male, who had undergone stereotactic radiation therapy 6 years ago for a presumed glomus jugulare tumor, presented to our institution with worsening dysphagia, hoarseness, persistent tongue weakness, and radiographic evidence of tumor progression. The patient underwent uncomplicated gross total resection with sacrifice of the infiltrated hypoglossal nerve. Histopathologic evaluation revealed anaplastic HPC/SFT (World Health Organization grade III). Review of the literature yielded 9 additional cases of JF HPC/SFT in 5 males (56%) and 4 females (44%), with a mean age of 49.6 years old. Patients commonly presented with pain (37.5%) and lower cranial nerve deficits (100%). Preoperative diagnoses included glomus jugulare (n = 2) or JF schwannomas (n = 3). All patients underwent microsurgical resection of the lesion, except for 1 who refused all treatment after diagnostic biopsy. CONCLUSION: The authors present the only reported case of anaplastic HPC of the JF. The illustrative case and those found on systematic review of the literature highlight the importance of tissue diagnosis and appropriate management.

Successful multidisciplinary treatment of Doege-Potter syndrome: hypoglycaemia caused by paraneoplastic IGF-2 production by a metastatic haemangiopericytoma.

Hypoglycaemia due to insulin-like growth factor (IGF)-2 secretion is a paraneoplastic complication of malignancy with significant morbidity that can often go unrecognised due to its uncommon presentation. We report on a case of a 51-year-old man with metastatic haemangiopericytoma presenting with refractory hypoglycaemia, requiring continuous dextrose 10% infusion while in hospital. IGF-2 levels were significantly elevated, in keeping with a rare entity associated with solitary fibrous tumours, known as Doege-Potter syndrome. The patient was managed using uncooked cornstarch in conjunction with debulking of the hepatic tumour burden with bland IR-guided transarterial embolisation, and eventual surgical resection to treat his non-islet cell tumour hypoglycaemia (NICTH). The case highlights this rare paraneoplastic phenomenon that should be included in the differential for hypoglycaemia, especially if a history of a solitary fibrous tumour is elicited. Our case is the first to document a successful approach to treating the hypoglycaemia using preoperative transarterial bland embolisation.

Tumor Biology Impacts Survival in Surgically Managed Primary Hepatic Vascular Malignancies.

BACKGROUND: Hepatic angiosarcoma (AS) and hepatic epithelioid hemangioendothelioma (HEHE) are rare primary hepatic vascular malignancies (PHVM) that remain poorly understood. To guide management, we sought to identify factors and trends predicting survival after surgical intervention using a national database. MATERIALS AND METHODS: In a retrospective analysis of the National Cancer Database patients with a diagnosis of PHVM were identified. Clinicopathologic factors were extracted and compared. Overall survival (OS) was estimated and predictors of survival were identified. RESULTS: Three hundred ninty patients with AS and 216 with HEHE were identified. Only 16% of AS and 36% of HEHE patients underwent surgery. The median OS for patients who underwent surgical intervention was 97 months, with 5-year OS of 30% for AS versus 69% for HEHE patients (P< 0.001). Tumor biology strongly impacted OS, with AS histology (Hazard Ratio [HR] of 3.61 [1.55-8.42]), moderate/poor tumor differentiation (HR = 3.86 [1.03-14.46]) and tumor size (HR = 1.01 [1.00-1.01]) conferring worse prognosis. The presence of metastatic disease in the surgically managed cohort (HR = 5.22 [2.01-13.57]) and involved surgical margins (HR = 3.87 [1.59-9.42]), were independently associated with worse survival. CONCLUSIONS: In this national cohort of PHVM, tumor biology, in the form of angiosarcoma histology, tumor differentiation and tumor size, was strongly associated with worse survival after surgery. Additionally, residual tumor burden after resection, in the form of positive surgical margins or the presence of metastasis, was also negatively associated with survival. Long-term clinical outcomes remain poor for patients with the above high-risk features, emphasizing the need to develop effective forms of adjuvant systemic therapies for this group of malignancies.

Hemangiopericytoma: Incidence, Treatment, and Prognosis Analysis Based on SEER Database.

BACKGROUND: Hemangiopericytomas are rare tumors derived from pericytes surrounding the blood vessels. The clinicopathological characteristics and prognosis of hemangiopericytoma patients remain mostly unknown. In this retrospective cohort study, we assessed the clinicopathological characteristics of hemangiopericytoma patients, as well as the clinical usefulness of different treatment modalities. Material and Methods. We collected the clinicopathological data (between 1975 and 2016) of hemangiopericytoma and hemangioendothelioma patients from the Surveillance, Epidemiology, and End Results (SEER) database. Incidence, treatment, and patient prognosis were assessed. RESULTS: Data from 1474 patients were analyzed in our study cohort (hemangiopericytoma: n = 1243; hemangioendothelioma: n = 231). The incidence of hemangiopericytoma in 2016 was 0.060 per 100,000 individuals. The overall survival (OS) and cancer-specific survival (CSS) did not differ between patients with hemangioendothelioma and those with hemangiopericytoma (P = 0.721, P = 0.544). The tumor grade had no effect on the OS of hemangiopericytoma patients. Multivariate analysis revealed the clinical usefulness of surgery in hemangiopericytoma patients (HR = 0.15, 95% confidence interval: 0.05-0.41, P < 0.001). In contrast, radiotherapy did not improve OS (P = 0.497) or CSS (P = 0.584), and chemotherapy worsened patient survival (P < 0.001). Additionally, the combination of surgery and radiotherapy had a similar effect with surgery alone on hemangiopericytoma patient survival (OS: P = 0.900; CSS: P = 0.156). Surgery plus chemotherapy provided a worse clinical benefit than surgery alone (P < 0.001). CONCLUSIONS: Our findings suggested that hemangiopericytoma had a similar prognosis with hemangioendothelioma. Surgery was the only effective treatment that provided survival benefits in hemangiopericytoma patients, while the clinical usefulness of adjuvant chemotherapy or radiotherapy was limited.

[What's new in the management of meningeal solitary fibrous tumor/hemangiopericytoma?] / Quoi de neuf dans la prise en charge des tumeurs fibreuses solitaires/hémangiopéricytomes des méninges ?

Meningeal fibrous solitary tumors/hemangiopericytoma are rare and aggressive mesenchymal neoplasms considered as sarcomas. They represent less than 1% of intracranial tumors and derive from the pericytes of Zimmerman which permit capillary contraction. They tend to occur more often in males in the fifth decade. They are often revealed by intracranial hypertension. Some scannographic and MRI characteristics permit to distinguish meningeal fibrous solitary tumor/hemangiopericytoma from other meningeal tumors. Meningeal hemangiopericytoma and fibrous solitary tumors were considered as different entities until 2016. Following the discovery of an identical genetic event, the locus 12q13 chromosome inversion leading to a NAB2-STAT6 fusion with nuclear immunoreactivity for STAT6 protein, the 2016 WHO classification defines these tumors as a single entity. Meningeal fibrous solitary tumors/hemangiopericytoma have a high recurrence rate. Long-term recurrences may occur. Local relapses are more frequent than extracranial metastasis. A multimodal management is recommended to treat a localized disease. It involves a complete resection followed by adjuvant radiotherapy. When local recurrences occur, surgery or stereotactic radiosurgery permit sometimes a local control. Metastatic disease has a poor prognostic and a weak chimiosensitivity. Targeted therapies, like pazopanib, are a hopeful option.

Metastatic intracranial solitary fibrous tumors/hemangiopericytomas: description of two cases with radically different behaviors and review of the literature.

Solitary fibrous tumor/hemangiopericytoma with primary tumor location in the central nervous system accounts for less than 1% of all central nervous system tumors. Despite the relatively indolent clinical course, extracranial metastases are reported in 28% of cases. In recent years, NAB2-STAT6 gene fusion has been recognized as the pathognomonic molecular feature of solitary fibrous tumor/hemangiopericytoma and STAT6 immunohistochemistry has been shown to be a sensitive and specific surrogate for the identification of the gene fusion in these patients. Here we report two cases of patients who experienced occurrence of diffuse extracranial metastases several years after successful surgery for an intracranial solitary fibrous tumor/hemangiopericytoma. In the first patient, the metastases had maintained similar histological features to the primary tumor; in contrast, in the second case, a dedifferentiation occurred with loss of expression of CD34 and Bcl-2. These different histological features were associated with radically different behaviors. Whereas the first case experienced an indolent course of the disease, the second patient had a rapid disease progression and deterioration of clinical conditions. The molecular imaging findings in these two cases and the role of functional imaging for tumor detection, disease staging and monitoring in this rare cancer are also discussed. Recurrences and metastases maintained high expression of somatostatin receptors confirmed by somatostatin receptor imaging in the first case. In contrast, in the second patient, the abrupt transition into a highly aggressive form was associated with the absence of somatostatin receptors at 111In Pentetreotide scan and intense hypermetabolism at 18F-FDG PET.

A rapidly fatal intracranial anaplastic hemangiopericytoma with de-novo dedifferentiation: emphasis on diagnostic recognition, molecular confirmation and discussion on treatment dilemma.

Solitary fibrous tumors/ hemangiopericytomas (SFT/HPC) are mesenchymal tumors that share a common genetic aberration and very rarely undergo dedifferentiation. We report a unique case of an intracranial anaplastic SFT/HPC with de-novo dedifferentiation, which pursued a rapidly fatal clinical course in a 41-year-old lady. The dedifferentiated component comprised a focal area of glandular formation with epithelial immunophenotype acquisition. The distinct biphasic pattern of the tumor imparted great diagnostic challenges to the pathologists. An increased awareness of SFT/HPCs with a diverse morphologic spectrum or even a biphasic histologic pattern is essential in working up such cases. We first attempted gamma knife radiosurgery in treating a recurrent dedifferentiated SFT/HPC; unfortunately it was to no avail. Although it is now known that SFT/HPC is characterized by NAB2-STAT6 gene fusion, the unavailability of targeted therapy against this molecular signature still results in a treatment dilemma.

Diagnosis and treatment of hemangiopericytoma in the central nervous system.

OBJECTIVE: This study aimed to explore the clinical characteristics and treatment of the hemangiopericytoma (HPC) in the central nervous system. MATERIALS AND METHODS: Clinical data from 14 patients with HPC in the central nervous system who were followed up for 12-107 months were retrospectively analyzed, and relevant literature was reviewed. RESULTS: All 14 patients underwent surgery and postoperative pathologic diagnosis, including 8 cases of total excision, 3 cases of subtotal excision, and 3 cases of partial excision. There were 7 recurrent cases (50%, 4 cases of total excision, 1 case of subtotal excision, and 2 cases of partial excision, none of them received postoperative radiotherapy) with a median relapse time of 39 months, where the median relapse time after total excision was 41.5 months, and after nontotal excision was 17 months. In addition, patients could survive for a long time after reoperation following relapse and after receiving postoperative radiotherapy. CONCLUSION: The diagnosis of HPC depends on the pathology. Currently, the surgery and postoperative radiotherapy provide a good treatment results, while the wholeness of surgical resection is of particular importance.

Diagnosis and treatment of solitary fibrous tumor/hemangiopericytoma of central nervous system. Retrospective report of 17 patients and literature review.

To investigate the diagnosis, treatment and prognosis of solitary fibrous tumor (SFT)/ hemangiopericytoma (HPC) of central nervous system (CNS), we retrospectively reviewed records of 17 patients who were treated for CNS SFT/HPC at the Department of Neurosurgery, China-Japan Union Hospital of Jilin University from December 2010 to June 2016, and reevaluated their pathological diagnoses according to the 2016 WHO classification of CNS tumors. We then analyzed their clinical symptoms, imaging characteristics, treatments and outcomes. Clinical manifestations of CNS SFT/HPC were diverse, but mainly included headache, increased intracranial pressure, seizures, and focal neurological deficits. In MRI, CNS SFT/HPC usually shows heterogeneous signals, and unusual enhancements; we saw lobulated shapes in 13 patients and necrotic or cystic changes in 12 patients. Tumors of all 17 patients were resected surgically; 9 patients also received postoperative adjuvant radiotherapy. Mean follow-up time was 21 months (range: 2-67 months). The 17 surgeries included 11 total resections, 4 subtotal resection, and 2 partial resections. We followed up 12 patients; 9 of the patients who received total resections had no disease progression; among the 6 patients who did not receive total resections, 2 died of tumor recurrence, 1 has not shown any disease progression. Thus, extent of resection has an apparently crucial influence on prognosis. Postoperative radiotherapy should be chosen carefully, based on resection extent and pathologic grade.

Association between programmed cell death ligand-1 expression and extracranial metastasis in intracranial solitary fibrous tumor/hemangiopericytoma.

BACKGROUND: Intracranial solitary fibrous tumor/hemangiopericytoma (SFT/HPC) often shows extracranial metastasis, and treatment options are very limited. Immune-checkpoint molecules have not been studied well in SFT/HPCs, and their role in intracranial SFT/HPCs remains unclear. METHODS: We investigated the expression of programmed cell death-1 (PD-1), programmed cell death ligand-1 (PD-L1), and tumor-infiltrating lymphocytes (TIL) in 16 patients of intracranial SFT/HPC by immunohistochemistry to determine if correlation with prognosis exists. RESULTS: Median overall survival (OS) of 16 patients was 9.2 years, and median follow-up of alive patients was 9.9 years. Recurrence was observed in 13 (81.3%) patients, and extracranial metastasis were observed in 6 (37.5%). PD-L1 expression was observed in all 16 tumors, whereas PD-1 expression was observed in 2. CD3 and CD8 expressions were observed in TILs in 12 and 13 patients respectively. Although the ratio of PD-L1 positive-tumor cells was not associated with OS, progression-free survival, or metastasis-free survival (MFS), diffuse staining of PD-L1 showed a trend toward shorter time to treatment failure (TTF: time to either extracranial metastasis or death) (p = 0.072). Similarly, the intense staining of PD-L1 was associated with shorter MFS (p = 0.0084) and TTF (p = 0.033). CD3 or CD8 expression was not associated with any of the prognostic parameters. In the combined analysis of PD-L1 and CD8, diffuse PD-L1 staining coupled with no or sparse CD8 expression was significantly associated with a shorter TTF (p = 0.005) and showed a trend toward shorter MFS (p = 0.0611). CONCLUSIONS: PD-L1 is frequently expressed in intracranial SFT/HPCs, and diffuse or intense PD-L1 expression might be associated with the early occurrence of extracranial metastases.

Solitary fibrous tumours and haemangiopericytoma of the meninges. A retrospective study for outcome and prognostic factor assessment.

BACKGROUND: To report on the outcome of patients diagnosed with central nervous system haemangiopericytoma (HPC) or solitary fibrous tumours (SFT) and identify factors that may influence recurrence and survival. MATERIAL AND METHODS: Between January 1977 and December 2016, a retrospective search identified 22 HPCs/SFTs. The patients underwent a total of 40 surgical resections and 63.6% received radiotherapy. Median follow-up was 7.8 years. RESULTS: Six patients (27.3%) were re-operated for tumour recurrence. At the end of the study, 15 patients (68.2%) had no residual tumour on the last imaging. Surgical recurrence-free survival at 5 years was 77.4%, [95% CI: 60.1-99.8]. None of the investigated variables was associated with recurrence. At the end of the study, 5 patients were deceased (22.7%) and only 10 patients (45.5%) had no residual tumour on the last imaging and were alive. Overall survival at 5 years was 95%, [95% CI: 85.9-100]. None of the investigated variables was associated with overall survival. Patients who received radiotherapy demonstrated neither a reduced risk of surgical recurrence (P=0.378) nor a longer overall survival (P=0.405). CONCLUSION: SFTs/HPCs are associated with a significant risk of recurrence that may reduce the survival. Even if we could not demonstrate their benefit in this limited series, we believe that tailored maximal tumour resection on initial surgery is beneficial and that adjuvant RT is useful for tumours displaying grade II or III, even in case of complete removal.

Infantile hemangiopericytoma of the tongue-Efficacy of ex utero intrapartum treatment procedure and combined-modality therapy.

Here we present an extremely rare case of giant infantile hemangiopericytoma (HPC) of the tongue diagnosed prenatally by fetal ultrasonography and MR imaging. Due to airway stenosis, the patient was delivered by the ex utero intrapartum treatment (EXIT) procedure at 36 weeks of pregnancy. Initial diagnosis was infantile hemangioma based on physical examination, diagnostic imaging and the high incidence of hemangioma. The tumor was resistant to conservative treatments. Due to severe tumor hemorrhage, the nutrient vessel was embolized by endovascular treatment on the 73th day after birth. Two days after embolization, a hemiglossectomy was performed. Histological analysis after surgery diagnosed infantile HPC with microscopically positive stumps. After receiving adjuvant chemotherapy, the patient has had no recurrence after 53 months with normal speech and swallowing function resulting in normal growth. Our findings support that infantile HPC is one of the differential diagnosis of infantile hemangioma. The EXIT procedure could be effective for infants with upper respiratory stenosis by head and neck tumor diagnosed prenatally. Though complete resection is required for infantile HPC, our report suggests that a conservative surgical approach followed by adjuvant chemotherapy should be used for giant head and neck infantile HPC.

Acquired Vascular Tumors of the Head and Neck.

Vascular neoplasms of the head and neck present with a wide spectrum of signs and symptoms. Diagnosis requires a high index of suspicion and is usually made after tumors are large enough to be visually apparent or cause symptoms. This article discusses the most common acquired benign and malignant vascular tumors, with an emphasis on their evaluation and treatment.

Meningeal haemangiopericytoma and solitary fibrous tumour: a retrospective bi centre study for outcome and prognostic factor assessment.

To describe the outcome of patients diagnosed with central nervous system haemangiopericytoma (HPC) or solitary fibrous tumour (SFT) and identify factors that may influence recurrence and survival. Between January 2000 and September 2016, a retrospective search identified 55 HPCs/SFTs. The patients underwent a total of 101 surgical resections and 56.9% received radiation therapy. Median follow-up was 7.8 years. 28 patients (50.9%) were re-operated for tumour recurrence. At the end of the study, 21 patients (42%) had no residual tumour on the last scan. Surgical recurrence-free survival at 5 years was 75.2%, 95% CI [63.3-89.3] and, the median surgical recurrence-free survival was 7.4 years. In the adjusted analysis, venous sinus invasion (present vs. absent) (HR 3.39, 95% CI [1.16, 9.93], p = 0.026), completeness of resection (HR 0.38, 95% CI [0.15-0.97], p = 0.042) and tumour subtype (SFT vs. HPC) (HR 3.02, 95% CI[1.02, 8.91], p = 0.045) were established as independent prognostic factors. At the end of the study, 25 patients were deceased (45.5%). and only 15 patients (27.3%) had no residual tumour on the last scan and were alive. Overall survival at 5 years was 80.2, 95% CI [69.3-92.8] and the median overall survival was 13.1 years. None of the investigated variables was associated with overall survival. Patients who received radiation therapy demonstrated neither a reduced risk of surgical recurrence (p = 0.370) nor a longer overall survival (p = 1.000). SFTs/HPCs are associated with a significant risk of recurrence that may reduce the survival of the patients. Total tumour resection upon initial surgery is associated with a lower risk of relapse but not with a prolonged survival. We did not observe a significant improvement in any of the clinical outcomes after radiation therapy.

Characteristics and prognosis of glomangiopericytomas: A systematic review.

BACKGROUND: Glomangiopericytoma belongs to the category of borderline/low-malignant-potential tumors of the sinonasal tract, but no studies about prognosis have been reported. METHODS: To define the characteristics of glomangiopericytoma and to identify its prognostic factors, a systematic review was performed. A total of 337 cases of glomangiopericytomas were analyzed. RESULTS: Patients with glomangiopericytoma demonstrating resection margin involvement and receiving radiotherapy/chemotherapy had a significantly worse disease-free survival time (P = .014 and .006, respectively). Patients with glomangiopericytoma had a tendency toward longer overall survival when they were diagnosed at a younger age (≤60 years; P = .001), did not demonstrate marginal involvement (P = .032), recurrence/metastasis (P = .002), or radiotherapy/chemotherapy (P = .010), and had a right-sided tumor (P < .001), actin-immunopositivity (P < .001), and CD34-/BCL2-immunonegativities (P = .002 and .019, respectively). By multivariate analysis, actin (P < .001) and CD34 (P = .002) immunostaining were significantly related to the overall survival of patients with glomangiopericytoma. CONCLUSION: Actin and CD34 immunostaining could be used as independent prognostic indicators of glomangiopericytomas.

Intraventricular Hemangiopericytoma: A Case Report and Literature Review.

BACKGROUND: Hemangiopericytomas are rare intracranial neoplasms that generally occur in the fifth decade of life and are commonly dural-based, supratentorial tumors. They are classified as World Health Organization grade II or III because of their aggressive nature with high rates of local recurrence and distant metastasis. This case is of an intraventricular hemangiopericytoma in a 23-year-old man. Intraventricular locations are rare, with only 10 cases reported in the literature. Our patient is the youngest to be diagnosed with an intraventricular hemangiopericytoma outside a pediatric case discovered at autopsy. CLINICAL PRESENTATION: A 23-year-old man with a left intraventricular hemangiopericytoma presenting with headache, word-finding difficulties, blurred vision, nausea, vomiting, photophobia, and right-sided weakness and numbness. Using a left superior parietal lobule approach, a piecemeal resection was completed, achieving radiographic gross total resection. Pathology was consistent with a hemangiopericytoma. He was treated adjunctively with 60 Gy of local radiation. At 6-month follow-up, the patient had resolution of his aphasia and improvement in his headaches, with no signs of recurrence or metastasis on imaging. CONCLUSIONS: Standard treatment for central nervous system hemangiopericytoma includes aggressive surgical resection. The role of adjuvant radiation is less well defined but is commonly pursued postoperatively. Regardless of extent of resection or adjuvant treatment, close follow-up to evaluate for evidence of local recurrence and distant metastasis is essential.

A population-based analysis of Head and Neck hemangiopericytoma.

OBJECTIVES/HYPOTHESIS: Hemangiopericytomas (HPC) are tumors that arise from pericytes. Hemangiopericytomas of the head and neck are rare and occur both extracranially and intracranially. This study analyzes the demographic, clinicopathologic, treatment modalities, and survival characteristics of extracranial head and neck hemangiopericytomas (HN-HPC) and compares them to HPCs at other body sites (Other-HPC). METHODS: The Surveillance, Epidemiology, and End Results (SEER) database (1973-2012) was queried for HN-HPC (121 cases) and Other-HPC (510 cases). Data were analyzed comparatively with respect to various demographic and clinicopathologic factors. Disease-specific survival (DSS) was analyzed using the Kaplan-Meier model. RESULTS: There was no significant difference in age at time of diagnosis between HN-HPC and Other-HPC. Head and neck HPC was most commonly located in the connective and soft tissue (18.4%), followed by the nasal cavity and paranasal sinuses (8.5%). Head and neck HPCs were smaller than Other-HPC (P < 0.0001) and more likely to be a lower histologic grade (P < 0.0097). The primary treatment modality for HN-HPC was surgery alone, used in 55.8% of cases. The 5-, 10-, and 20-year DSS for HN-HPC were 84.0%, 79.4%, and 69.4%, respectfully. Higher histologic grade and the presence of distant metastases were poor prognostic factors for HN-HPC. CONCLUSION: Head and neck HPCs are rare tumors. This study represents the largest series of HN-HPCs to date. Surgery alone is the primary treatment modality for HN-HPC, with a favorable prognosis. Adjuvant radiotherapy does not appear to confer a survival benefit for any body site. LEVEL OF EVIDENCE: 4. Laryngoscope, 126:643-650, 2016.