Squamous and Neuroendocrine Specific Immunohistochemical Markers in Head and Neck Squamous Cell Carcinoma: A Tissue Microarray Study

High-grade neuroendocrine head and neck cancer: Case series and review of the literature

BACKGROUND

High-grade neuroendocrine cancers (NEC) of the head and neck (HN) are rare and aggressive, accounting for ≤1 % of all HN cancers, with a 5-year overall survival (OS) of ≤20 %. This case series examines clinical characteristics, treatments, and outcomes of patients diagnosed at a regional UK HN cancer centre over the last 23 years.

METHODS

A retrospective review of medical records was conducted for all patients diagnosed with NEC HN from 1st January 2000 until 1st March 2023 at Velindre Cancer Centre.

RESULTS

During the study period, 19 cases of NEC HN were identified, primarily affecting males (n = 15, 79 %). Median age of 67 years (range: 44-86). At diagnosis, 32 % of patients (n = 6) were smokers. The most common primary tumour sites were larynx (n = 5, 26.3 %) and sinonasal (n = 5, 26.3 %). Most patients presented with advanced loco-regional disease or distant metastasis, with stage IVA (n = 6, 32 %) and stage IVC (n = 6, 32 %) being the most common. The key pathology marker was synaptophysin, present in 100 % of the tested patients (n = 15). In the study, of the 12 patients with non-metastatic disease, 10 received a combination of treatments that included radiotherapy (RT). Some of these patients also received chemotherapy (CT) at the same time as their radiotherapy. Surgery alone was used in two patients with stage II disease. Seven subjects had complete responses, and one achieved a partial response. Among the seven metastatic patients, three received CT, and one underwent palliative RT, all achieving a partial response. In all cases, the CT used was carboplatin and etoposide. After a median follow-up of 11 months (range: 1-96), the median OS was 27 months for the overall population, 51 months for those treated radically, and three months for metastatic patients with palliative treatment. The 1-year OS for all patients was 54.3 %, the 2-year OS was 46.5 %, and the 5-year OS was 23.3 %. Among patients treated radically, these rates were 65.3 %, 52.2 %, and 26.1 %, respectively. For patients treated palliatively, the 1-year OS was 33.3 %.

CONCLUSION

This case series contributes preliminary observations on the characteristics and management of non-metastatic NEC HN, suggesting potential benefits from multimodality treatment strategies. Given the small cohort size, these observations should be interpreted cautiously and seen as a foundation for further research.

Reduced expression of secretogranin VGF in laryngeal squamous cell carcinoma

Laryngeal cancer accounts for one-third of all head and neck tumors, with squamous cell carcinoma (SCC) being the most predominant type, followed by neuroendocrine tumors. Chromogranins, are commonly used as biomarkers for neuroendocrine tumors, including laryngeal cancer. It has been reported that secretogranin VGF, a member of the chromogranin family, can be also used as a significant biomarker for neuroendocrine tumors. However, the expression and role of VGF in laryngeal carcinomas have not been previously investigated. Therefore, the present study aimed to determine the expression levels of VGF in laryngeal SCC (LSCC). The present study collected tumor tissues, as well as serum samples, from a cohort of 15 patients with LSCC. The results of reverse transcription-quantitative PCR, western blot analysis and immunofluorescence assays showed that the selective VGF precursor was downregulated in patients with LSCC. Notably, in tumor tissue, the immunoreactivity for VGF was found in vimentin-positive cells, probably corresponding to T lymphocytes. The current preliminary study suggested that the reduced expression levels of VGF observed in tumor tissue and at the systemic level could sustain LSCC phenotype. Overall, VGF could be a potential biomarker for detecting neoplastic lesions with a higher risk of tumor invasiveness, even in non-neuroendocrine tumors.

Palisading Adenocarcinoma: A Morphologically Unique Salivary Gland Tumor With a Neuroendocrine-like Appearance and a Predilection for the Sublingual Glands of Women

Adenocarcinoma, not otherwise specified (NOS) is a heterogenous group of salivary gland tumors that likely contains distinct tumors that have not yet been characterized. Indeed, in recent years, cases previously diagnosed as adenocarcinoma, NOS have been recategorized into novel tumor designations such as secretory carcinoma, microsecretory adenocarcinoma, and sclerosing microcystic adenocarcinoma. We sought to describe a distinctive, hitherto-undescribed salivary gland tumor encountered in the authors' practices. Cases were pulled from the surgical pathology archives of the authors' institutions. Histologic, immunohistochemical, and clinical findings were tabulated, and targeted next-generation sequencing was performed on all cases. Nine cases were identified, arising in 8 women and 1 man ranging from 45 to 74 years (mean, 56.7 y). Seven tumors (78%) arose in the sublingual gland, while 2 (22%) arose in the submandibular gland. The cases shared a distinctive morphologic appearance. They were biphasic, with ducts scattered among a predominant polygonal cell with round nuclei, prominent nucleoli, and pale eosinophilic cytoplasm. These cells were arranged as trabeculae and palisaded as pseudorosettes around hyalinized stroma and vessels, resembling a neuroendocrine tumor. Four of the cases were well-circumscribed, while the remaining 5 showed infiltrative growth including perineural invasion in 2 (22%) and lymphovascular invasion in 1 (11%). Mitotic rates were low (mean, 2.2/10 HPFs); necrosis was absent. By immunohistochemistry, the predominant cell type was strongly positive for CD56 (9 of 9) and variably positive for pan-cytokeratin (AE1/AE3) (7 of 9) with patchy S100 (4 of 9), but negative for synaptophysin (0 of 9) and chromogranin (0 of 9), while the ducts were strongly positive for pan-cytokeratin (AE1/AE3) (9 of 9) and CK5/6 (7 of 7). Next-generation sequencing did not reveal any fusions or obvious driver mutations. All cases were resected surgically, with external beam radiation also done in 1 case. Follow-up was available in 8 cases; there were no metastases or recurrences after 4 to 160 months (mean, 53.1 mo). A dual population of scattered ducts with a predominance of CD56-positive neuroendocrine-like cells characterizes a unique salivary gland tumor which is often encountered in the sublingual glands of women, for which we propose the term "palisading adenocarcinoma." Although the tumor was biphasic and had a neuroendocrine-like appearance, it lacked convincing immunohistochemical evidence of myoepithelial or neuroendocrine differentiation. Although a subset showed unequivocally invasive growth, this tumor appears to behave in an indolent manner. Moving forward, recognition of palisading adenocarcinoma and its separation from other salivary adenocarcinomas, NOS will facilitate a better understanding of the characteristics of this previously unrecognized tumor.

Adamantinoma-like ewing sarcoma arising in the pancreatic tail: a case report of a rare entity and review of the literature

ALES is a rare subtype that demonstrates the EWSR1-FLI1 translocation characteristic of ES and demonstrates complex epithelial differentiation including diffuse cytokeratin and p40 expression. It has predominantly recognized in the head and neck and is common in middle-aged population. This case is the first case of ALES reported in the pancreatic tail, sharing some morphological characteristics with ALES in the head and neck, including monotonous cytology, infiltrative growth pattern, and complex epithelioid differentiation, but ALES in the head and neck often has high-grade histological features (e.g., necrosis, high mitotic rate, etc.), and sudden keratinization can also occur, but these features were not reflected in this primary pancreatic tail ALES. Although ALES arising in the pancreatic tail and in the head and neck sites share the immunohistochemical and molecular profile, our case can provide new ideas in differential diagnosis of ALES arising in pancreatic tail and promote increased recognition and understanding of ALES.

Tumor-Stroma Ratio in Basaloid and Conventional Laryngeal Squamous Cell Carcinoma: Prognostic Significance and Concordance in Paired Biopsies and Surgical Samples

Basaloid squamous cell carcinoma (BSCC) is a subtype of squamous cell carcinoma (SCC) associated with a poor prognosis. Tumor–stroma ratio (TSR) has been introduced as a prognostic feature in many solid tumors. TSR was investigated in a series of laryngeal BSCCs and compared with a group of stage-matched conventional SCCs (cSCCs), in both preoperative and surgical specimens, with the intent of ascertaining the more aggressive behavior of BSCC and verifying the presence of stromal-related causes. A series of 14 consecutive laryngeal BSCCs and a control group of 28 stage-matched conventional cSCCs were analyzed. A higher nodal metastasis presence was found in BSCCs (57.1% vs. 28.6%). The recurrence rate was 33.5% and 63.6% in the cSCC and BSCC groups; disease-free survival (DFS) was higher, though not significantly, in patients with cSCC. TSR, large cell nests, and tumor budding showed a moderate to very good agreement, and stroma type a good to very good agreement between biopsies and surgical specimens in the cSCC group. In the BSCC group, agreement was poor to very good for TSR and stroma type, and good to very good for large cell nests and tumor budding. Age was the only feature significant in predicting recurrence in the BSCC group (p = 0.0235). In cSCC, TSR low/stroma rich cases, when evaluated on biopsies or surgical specimens, were associated with lower DFS (p = 0.0036; p = 0.0041, respectively). Laryngeal BSCCs showed a lower DFS than cSCCs, even if statistical significance was not reached. TSR, evaluated in laryngeal biopsies and excised tumors, was prognostic in terms of DFS in cSCC but not in BSCC cases.

Top 10 Basaloid Neoplasms of the Sinonasal Tract

BACKGROUND

Basaloid neoplasms of the sinonasal tract represent a significant group of tumors with histological overlap but often with different etiologies (i.e., viral, genetics), clinical management, and prognostic significance.

METHODS

Review.

RESULTS

"Basaloid" generally refers to cells with coarse chromatin in round nuclei and sparse cytoplasm, resembling cells of epithelial basal layers or imparting an "immature" appearance. Tumors with this characteristic in the sinonasal tract are represented by a spectrum of benign to high-grade malignant neoplasms, such as adenoid cystic carcinoma, NUT carcinoma, sinonasal undifferentiated carcinoma, SWI/SNF complex-deficient carcinomas, and adamantinoma-like Ewing sarcoma.

CONCLUSION

In some instances, histology alone may be sufficient for diagnosis. However, limited biopsy material or fine-needle aspiration specimens may be particularly challenging. Therefore, often other diagnostic procedures, including a combination of histology, immunohistochemistry (IHC), DNA and RNA testing, and molecular genetics are necessary to establish an accurate diagnosis.

A diagnostic pitfall; Small cell carcinoma-like features in basaloid squamous cell carcinoma of the esophagus

Esophageal basaloid squamous cell carcinoma may resemble small cell carcinoma biopsy specimens and cause difficulties in pathology diagnosis. We aimed to clarify the clinicopathological significance of small cell carcinoma-like morphologies in basaloid squamous cell carcinoma. Thirty biopsy specimens of esophageal basaloid squamous cell carcinoma were reviewed and compared with 13 matched surgical specimens. Small cell carcinoma-like features, such as diffuse growth, nuclear molding, or nuclear crush artifact, were identified in 80% (24/30) of the biopsies and in 77% (10/13) of the surgery specimens, but in a proportionally much smaller area in the surgical specimens than in the biopsy samples. The presence of a small cell carcinoma-like feature had no impact on patients´ outcome. Immunohistochemically, synaptophysin and chromogranin A were consistently negative, while CD56 was expressed in 42% (10/24) of basaloid squamous cell carcinomas with small cell carcinoma-like features. p16, a highly sensitive marker for small cell carcinoma, was also expressed in 8% (2/24). p40 was expressed in all cases of basaloid squamous cell carcinoma. In conclusion, small cell carcinoma-like features are frequent and conspicuous in biopsies, which are probably caused by exogenous factors such as friction and external pressure that occur in biopsy procedure and in the tumor environment. Small cell carcinoma-like features may lead to a misinterpretation of a true small cell carcinoma, if CD56 is the only neuroendocrine marker expressed. p16 expression may also be detected in basaloid squamous cell carcinoma.

Evaluation of Heterogeneous Nuclear Ribonucleoprotein D Expression as a Diagnostic Marker for Oral Squamous Cell Carcinoma

The heterogeneous nuclear ribonucleoprotein D (hnRNPD) serves as a prognostic marker for oral squamous cell carcinoma (OSCC). We evaluated the diagnostic potential of hnRNPD to differentiate between OSCC and normal mucosa. Immunohistochemistry for hnRNPD and a routinely used diagnostic marker deltaNp63 (p40) was performed in 32 normal mucosae and 46 OSCC specimens. Subsequently, receiver-operating characteristic analysis was performed to evaluate the diagnostic potential of hnRNPD in comparison to that of p40. Immunostaining for p40 and hnRNPD was observed in 39 (84.78%) and 38 (82.60%) cases, respectively, in OSCC specimens. The poorly differentiated squamous cell carcinoma displayed 100% (eight cases) immunoreactivity for hnRNPD as compared to 87.5% (seven cases) for p40. Nuclear staining of p40 and hnRNPD was observed in all OSCC specimens. p40 staining was restricted to basal cells, whereas both basal and para-basal cells displayed hnRNPD staining in OSCC specimens. Areas under the curve for p40 and hnRNPD were 0.86 and 0.87, respectively. p40 and hnRNPD showed equal sensitivities (80.95%). However, hnRNPD displayed marginally higher (88.23%) specificity for tumor cells as compared to that of p40 (85.29%). Conclusion: In addition to being a well-established prognostic marker, hnRNPD can serve as a diagnostic marker for OSCC.

Overview of the 2022 WHO Classification of Neuroendocrine Neoplasms

In this review, we detail the changes and the relevant features that are applied to neuroendocrine neoplasms (NENs) in the 2022 WHO Classification of Endocrine and Neuroendocrine Tumors. Using a question-and-answer approach, we discuss the consolidation of the nomenclature that distinguishes neuronal paragangliomas from epithelial neoplasms, which are divided into well-differentiated neuroendocrine tumors (NETs) and poorly differentiated neuroendocrine carcinomas (NECs). The criteria for these distinctions based on differentiation are outlined. NETs are generally (but not always) graded as G1, G2, and G3 based on proliferation, whereas NECs are by definition high grade; the importance of Ki67 as a tool for classification and grading is emphasized. The clinical relevance of proper classification is explained, and the importance of hormonal function is examined, including eutopic and ectopic hormone production. The tools available to pathologists for accurate classification include the conventional biomarkers of neuroendocrine lineage and differentiation, INSM1, synaptophysin, chromogranins, and somatostatin receptors (SSTRs), but also include transcription factors that can identify the site of origin of a metastatic lesion of unknown primary site, as well as hormones, enzymes, and keratins that play a role in functional and structural correlation. The recognition of highly proliferative, well-differentiated NETs has resulted in the need for biomarkers that can distinguish these G3 NETs from NECs, including stains to determine expression of SSTRs and those that can indicate the unique molecular pathogenetic alterations that underlie the distinction, for example, global loss of RB and aberrant p53 in pancreatic NECs compared with loss of ATRX, DAXX, and menin in pancreatic NETs. Other differential diagnoses are discussed with recommendations for biomarkers that can assist in correct classification, including the distinctions between epithelial and non-epithelial NENs that have allowed reclassification of epithelial NETs in the spine, in the duodenum, and in the middle ear; the first two may be composite tumors with neuronal and glial elements, and as this feature is integral to the duodenal lesion, it is now classified as composite gangliocytoma/neuroma and neuroendocrine tumor (CoGNET). The many other aspects of differential diagnosis are detailed with recommendations for biomarkers that can distinguish NENs from non-neuroendocrine lesions that can mimic their morphology. The concepts of mixed neuroendocrine and non-neuroendocrine (MiNEN) and amphicrine tumors are clarified with information about how to approach such lesions in routine practice. Theranostic biomarkers that assist patient management are reviewed. Given the significant proportion of NENs that are associated with germline mutations that predispose to this disease, we explain the role of the pathologist in identifying precursor lesions and applying molecular immunohistochemistry to guide genetic testing.

Surgical palliation in poorly differentiated neuroendocrine carcinoma of the hypopharynx: Case report

Background

Primary neuroendocrine carcinomas (NECs) are very rare entities accounting for 0.49% of all malignancies. Within the head and neck, the most common sites are the larynx and paranasal sinuses, while the hypopharynx is seldom described.

Case

We present a patient with a poorly differentiated metastatic NEC of the hypopharynx treated palliatively with organ‐preserving surgery and post‐operative chemotherapy, and literature review for well‐documented pure hypopharyngeal NECs. Our patient died of chest infection during chemotherapy, 4 months after surgery.

Conclusion

Chemotherapy remains the mainstay of treatment in the presence of metastases with 2‐year overall survival of 15.7%. Due to the aggressive nature of poorly differentiated metastatic NECs, surgical management is seldom considered. We report and advocate the successful palliative role of organ‐preserving, minimally invasive trans‐oral LASER micro‐surgery and neck dissection to control loco‐regional head and neck disease, safe‐guarding better quality of home life, despite limited life expectancy for this condition.

Neuroendocrine carcinomas of the head and neck: A small case series

INTRODUCTION

Neuroendocrine tumors of the head and neck are rare and arise either from epithelial or neuronal origin. Debate continues over the classification systems and appropriate management of these pathologies.

OBJECTIVE

By investigating a small set of cases of high grade epithelial-derived neuroendocrine tumors of the head and neck (neuroendocrine carcinomas or NEC) from one institution, we compare survival rates of NEC of the head and neck to pulmonary NEC.

METHODS

We identified patients from pathology records with neuroendocrine carcinomas of the head and neck and retrospectively collected clinical data as well as immunohistochemical (IHC) staining data.

RESULTS

We identified 14 patients with NEC, arising from the parotid (n = 5), nasal cavity (n = 4), larynx (n = 2), and other regions (n = 2). One additional patient had NEC arising in two sites simultaneously (parotid and nasal). Staining patterns using IHC were relatively consistent across specimens, showing reactivity to chromogranin and synaptophysin in 73% and 100% of specimens, respectively. Treatment courses varied across patients and included combinations of surgery, chemotherapy, and/or radiation. The overall survival rate at 1, 2, and 5 years of these patients was 56%, 56%, and 43% with a mean follow-up time of 2.12 years.

CONCLUSION

Compared to NEC arising in the lung, this subset of patients had better survival rates, but worse survival rates than the more common squamous cell carcinoma of the head and neck.

CD56 expression in basaloid anal squamous cell carcinoma - A potential diagnostic pitfall

Anal squamous cell carcinoma (SqCC) is a morphologically heterogeneous entity. Basaloid and non-keratinizing anal SqCC may be confused with other tumors including neuroendocrine carcinoma due to morphologic overlap, and expression of neuroendocrine markers is not well-studied in anal SqCC. Prompted by a case of anal SqCC that was initially misdiagnosed as neuroendocrine carcinoma on the basis of morphology and CD56 expression, we retrospectively examined the expression of neuroendocrine markers CD56, synaptophysin, and chromogranin in 48 cases of basaloid anal SqCC, with clinicopathologic correlation. HPV16 was identified in 46 cases, HPV33 in one case, and one case was HPV-negative. Three (6.3%) cases demonstrated CD56 expression, including two with diffuse and one with focal expression. Two CD56-positive cases demonstrated basaloid morphology with peripheral palisading and the other demonstrated adenoid cystic/cylindroma-like morphology. None of the cases showed significant synaptophysin or chromogranin expression. The three cases expressing CD56 were HPV16-positive, and one demonstrated a CTNNB1 mutation. There was no difference in clinicopathologic features including stage, outcome, or HPV status, between CD56-positive and negative groups. Our findings support that CD56 expression is infrequently expressed in anal SqCC and is not indicative of neuroendocrine differentiation in the absence of expression of more specific neuroendocrine markers such as synaptophysin and chromogranin. Pathologists should be aware that CD56 expression may occur in basaloid anal SqCC and is a diagnostic pitfall due to morphologic overlap with neuroendocrine carcinoma and other tumors including basal cell carcinoma.

Application of INSM1 in Diagnosis and Grading of Laryngeal Neuroendocrine Carcinoma

OBJECTIVE

Chromogranin (CHG), synaptophysin (Syn), and CD56 are generally used in a panel to support diagnoses of laryngeal neuroendocrine carcinomas (NECs). However, the absence of expression of these markers does not completely exclude the diagnosis. INSM1 is a novel marker that is considered sufficiently sensitive and specific for NE differentiation. The aim of this study is not only to detect its sensitivity and specificity, but also to evaluate its application in grading for laryngeal NECs.

METHODS

The clinicopathological characteristics of the 25 cases with laryngeal NECs were retrospectively analyzed. The expressions of INSM1, CHG, Syn, and CD56 were detected by immunohistochemistry.

RESULTS

Of the 25 laryngeal NECs, INSM1 had higher sensitivity (92%) than Syn (84%), CHG (76%) and CD56 (76%). The average H scores of INSM1, CD56, Syn, and CHG were 160, 37.5, 300, 300 for well-differentiated neuroendocrine carcinoma (WD-NEC); 190, 149, 209, 215 for moderately differentiated neuroendocrine carcinoma (MD-NEC); 251, 208, 104, 25 for poorly differentiated neuroendocrine carcinoma with small cell (SCNEC); 109, 160, 98, 26 for large cell types (LCNEC), respectively. Of these 98 non-neuroendocrine tumors, INSM1 expression was seen in nine (9%) tumors, all were squamous cell carcinoma. And INSM1 staining was generally focal.

CONCLUSION

INSM1 has high sensitivity and specificity in diagnosis of laryngeal NECs. For grading laryngeal NECs, Syn and CHG showed significant advantages in the diagnosis of WD-NEC and MD-NEC, whereas INSM1 and CD56 showed greater diagnostic value in the diagnosis of SCNEC and LCNEC, especially in SCNEC.

LEVEL OF EVIDENCE

4 Laryngoscope, 2021.

HPV-related carcinoma of the oropharynx: challenges on small biopsy specimens

Human papillomavirus (HPV)-related oropharyngeal carcinoma can morphologically mimic many processes from benign to malignant and lead pathologists to incorrectly diagnose them and/or use inappropriate diagnostic terminology. Recognition of HPV-related oropharyngeal carcinoma and its variants is critical for appropriate prognostic and therapeutic considerations in small biopsy material. Various pitfalls in diagnosing these tumors on limited biopsies are discussed herein.

Primary Combined Small-Cell and Squamous Cell Carcinoma of the Supraglottis: Case Report and Literature Review

Combined small-cell carcinoma and squamous cell carcinoma of the larynx is an exquisitely rare and underreported primary tumor the head and neck region, with an English literature review revealing only 17 documented cases. There is limited information on how best to treat these patients oncologically, given the low number of reported cases. A subset of the reported cases also detail a unique local spread of this combined carcinoma, further obscuring the clinical picture of these patients. Here, we detail an 18th case, with nodal metastasis of only one component of the primary tumor, and discuss the published literature surrounding this etiology.

Update on Neuroendocrine Carcinomas of the Larynx

OBJECTIVES

Laryngeal neuroendocrine carcinomas are heterogeneous neoplasms characterized by neuroendocrine differentiation. Their prognoses are dependent on tumor type, therefore different classifications have been developed. Moreover, other tumors have overlapping pathologic features posing a range of diagnostic possibilities.

METHODS

A review of the literature was performed to comprehensively understand the classification and diagnosis of these tumors.

RESULTS

We review the past and present classification systems, with emphasis to the latest 2017 World Health Organization Classification of Head and Neck Tumors. We highlight salient clinicopathologic features and discuss the presumptive etiologic role of human papilloma virus. We share a practical algorithmic approach to the diagnosis of suspected neuroendocrine neoplasms of the larynx including a novel marker for neuroendocrine differentiation, insulinoma-associated protein 1.

CONCLUSIONS

Accurate diagnosis and grading of laryngeal neuroendocrine carcinomas is critical for prognostication and therapeutic decision making. The use of an algorithm is instrumental in assuring the exclusion of mimickers.

Synchronous peritoneal carcinomatosis from a buccal squamous cell carcinoma: a case report focusing on possible metastatic mechanisms and novel therapeutic modalities

A 53-year-old male patient was diagnosed with squamous cell carcinoma of buccal mucosa with synchronous diffuse peritoneal carcinomatosis, a very rare presentation for oral cancer. His disease was highly resistant to intensive systemic chemotherapy and progressed rapidly. So far as we know, there were only five cases with peritoneal involvement by metastatic head and neck cancer reported prior to this patient in the English literature. Immunohistochemistry study revealed that tumour specimens from both oral cavity and peritoneum were negative for tumour necrosis factor alpha and CD24 but positive for CD44 and CD36. These four molecules have been disclosed to be involved in the process of peritoneal metastasis from ovarian cancer. Their roles in the metastatic pathway and possible therapeutic policy targeting at them will be thoroughly discussed.

Diagnostic traps awaiting the head/neck pathologist: "Cytoplasm-poor" neoplasms

CONTEXT

Beyond squamous carcinoma, a variety of diagnostically challenging neoplasms arise within various head and neck sites. This is particularly the situation with neoplasms where little cellular cytoplasm is present to assist the pathologist in categorizing such lesions.

OBJECTIVE

To highlight diagnostic pitfalls that accompanying neoplasms composed primarily of 'cytoplasmically-poor' cells. These pitfalls include morphologic and immunohistochemical traps that emerge from this class of neoplasms.

DATA SOURCES

Selection of pathologic specimens from the author's personal files, and literature review.

CONCLUSIONS

Interpretative pitfalls regarding the histopathology and immunophenotype of small 'cytoplasmically-poor' neoplasms are a diagnostic hazard in head and neck surgical pathology practice, and require knowledge of histomorphologic plasticity and aberrant immunophenotyping.

Cytopathologic characteristics of HPV-related small cell carcinoma of the oropharynx

BACKGROUND

Human papillomavirus (HPV)-related squamous cell carcinoma (SqCC) of the oropharynx is an epidemiologically and clinically distinct form of SqCC that is associated with an improved prognosis. However, HPV-related small cell carcinoma of the oropharynx is a rare and newly described variant that is associated with aggressive clinical behavior and poor outcomes. To date, fewer than 2 dozen reports of this entity exist in the literature, and there is no discussion of cytopathologic features. This article reports 6 cases and discusses the salient cytomorphologic findings, ancillary studies, and challenges when this entity is encountered.

METHODS

Anatomic pathology archives were searched to identify patients with a diagnosis of HPV-related small cell carcinoma of the oropharynx. Medical records were reviewed to document the following: age, sex, smoking status, other relevant clinical history, primary location, treatment, and clinical outcome. Both p16 and high-risk HPV in situ hybridization (ISH) studies were positive in at least 1 specimen from each patient. The pathologic diagnoses, cytomorphologic characteristics, immunocytochemical stains, and HPV ISH studies were reviewed and recorded for all available cases.

RESULTS

Six patients with 11 cytopathology specimens of HPV-related small cell carcinoma of the oropharynx were identified. The mean age was 61.3 years, and all patients died with widely metastatic disease (mean, 23 months; range, 12-48 months). Mixed small cell carcinoma and SqCC components were present in half of the cases.

CONCLUSIONS

The identification of a small cell component can be reliably performed with cytology preparations and is crucial because this (and not the HPV status) determines the prognosis.

Human Papillomavirus-Related Neuroendocrine Carcinomas of the Head and Neck

Human papillomavirus (HPV)-related head and neck carcinoma (HNC) represents an important subgroup of head and neck cancer that is characterized by a consistent microscopic appearance and a favorable prognosis. A growing experience with HPV testing, however, has uncovered variants that deviate from the prototypic HPV-HNC with respect to morphology. While these HPV-HNCs may deviate morphologically from the prototype, they do not appear to stray far from the favorable clinical outcome assigned to HPV-positive status. In effect, HPV positivity trumps traditional prognostic features predicated on morphology such as tumor grade and histologic subtype when it comes to predicting clinical behavior. For the diagnostic pathologist, the pedestrian task of tumor grading and subtyping would seem to be of little prognostic or therapeutic relevance when it comes to HPV-HNC. Recognition and documentation of neuroendocrine differentiation is a most notable exception. Forms of HPV-HNC have now been reported that morphologically resemble small cell carcinoma (SCC) and large cell neuroendocrine carcinoma (LCNEC) of other sites, and that immunohistochemically exhibit neuroendocrine differentiation. Despite the presence of HPV, these SCCs and LCNECs share the same aggressive clinical behavior of their counterparts in the lung and other sites where the high grade neuroendocrine phenotype is associated with early distant spread and poor overall survival. Consequently, the high grade neuroendocrine phenotype should be regarded as an aggressive form of HPV-HNC where tumor morphology displaces HPV positivity as the most important prognostic feature.