p40 is a more specific marker than p63 for cutaneous poorly differentiated squamous cell carcinoma

A case of fine-needle aspiration of a neck mass with atypical squamous cells and macrophages

Head and neck lesions often undergo fine-needle aspiration to determine the appropriate management and therapeutic decisions. However, there are numerous diagnostic challenges encountered with these specimens, particularly, if atypical squamous cells are identified. Here, we present a case of an enlarging right neck mass in a 38-year-old female and discuss the diagnostic difficulties and potential pitfalls. Additionally, we review the approach to diagnosis, including differential diagnostic considerations as well as available ancillary testing.

Metastatic Axillary Cutaneous Squamous Cell Carcinoma in an African-American Female: A Rare Case

Cutaneous squamous cell carcinoma (cSCC) is a common skin cancer, typically affecting older White males in sun-exposed areas, and metastasis is rare. We present a unique case of a 46-year-old obese African-American woman with a recurrent, deep abscess in her left axilla. It was initially treated with several incision and drainage procedures and antibiotics. Despite multiple interventions, the abscess recurred with severe pain and drainage. Subsequent biopsies revealed a high-grade malignant neoplasm, later confirmed as poorly differentiated cSCC with primary metastases to the lungs and secondary metastases to the adrenal glands and periaortic lymph nodes. Immunohistochemical staining supported the diagnosis. The patient's atypical presentation, including her race, a non-sun-exposed site, and younger age, highlights the need for vigilance in diagnosing cSCC in atypical cases. This case underscores the importance of early consideration of cSCC in differential diagnoses for persistent or recurrent abscesses, which can facilitate timely treatment, potentially preventing extensive metastasis and improving patient outcomes.

A collision tumor of basal cell carcinoma and atypical fibroxanthoma: A case report

An 83-year-old man presented an elevated skin lesion in the left temporal area. The resected specimen was identified between a basal cell carcinoma and an atypical fibroxanthoma. A final diagnosis of basal cell carcinoma and atypical fibroxanthoma was made. This study reports a rare case of a cutaneous collision.

Acantholytic squamous cell carcinoma mimicking epithelioid angiosarcoma: A diagnostic challenge by cytology

Squamous cell carcinoma (SCC) is the most common malignancy of the head and neck region. Most cases present little diagnostic difficulty on fine needle aspiration (FNA), but unusual variants can be problematic. The authors report a case of the acantholytic SCC of the oral cavity in a 36-year-old male. The FNA showed hypercellularity, with malignant cells arranged in isolation, loosely cohesive groups and a linear configuration. Such cells were round to elongated, with vesicular nuclei and prominent nucleoli. Cells possessed occasional intracytoplasmic vacuoles, misinterpreted on FNA to be vasoformative features as seen in malignant endothelial cells. The cytologic diagnosis was "positive for malignancy, suggestive of angiosarcoma". A total excision was performed and by histology, the tumor was diagnosed as acantholytic SCC. The malignant cells were positive by immunostaining for AE1/AE3, p40, p63 and vimentin, but negative for CD31, CD34 and ERG. The intracytoplasmic vacuoles were PAS- and mucin-negative and negative for the above antibodies. Testing for HPV (molecular and p16 immunostaining) was negative. This case highlights the diagnostic challenges on cytology when malignant acantholytic squamous cells show intracytoplasmic vacuoles, and stresses how immunohistochemistry is important for distinguishing acantholytic SCC from other mimics.

Different expression patterns of p63 and p73 in Felis catus papillomavirus type 2-associated feline Merkel cell carcinomas and other epidermal carcinomas

Merkel cell carcinoma (MCC) is a cutaneous neuroendocrine tumor, and more than 90% of feline MCC cases test positive for Felis catus papillomavirus type 2 (FcaPV2). In the present study, basal cell markers p40, p63, and p73 and the stem cell marker SOX2 and cytokeratin 14 (CK14) were immunohistochemically examined in normal fetal, infant, and adult feline skin tissues. The expression of these proteins was examined in tumors positive for FcaPV2, including MCC, basal cell carcinoma (BCC), Bowenoid in situ carcinoma (BISC), and squamous cell carcinoma (SCC). Infant and adult feline skin tissues had mature Merkel cells, which were CK14-, CK18+, CK20+, SOX2+, synaptophysin+ and CD56+, while fetal skin tissue had no mature Merkel cells. MCC was immunopositive for p73, CK18, and SOX2 in 32/32 cases, and immunonegative for CK14 in 31/32 cases and for p40 and p63 in 32/32 cases. These results indicate that MCC exhibits different immunophenotypes from Merkel cells (p73-) and basal cells (p40+, p63+, and SOX2-). In contrast, all 3 BCCs, 1 BISC, and 2 SCCs were immunopositive for the basal cell markers p40, p63, and p73. The life cycle of papillomavirus is closely associated with the differentiation of infected basal cells, which requires the transcription factor p63. Changes in p63 expression in FcaPV2-positive MCC may be associated with unique cytokeratin expression patterns (CK14-, CK18+, and CK20+). Furthermore, SOX2 appears to be involved in Merkel cell differentiation in cats, similar to humans and mice.

Expression of SATB2 in primary cutaneous sarcomatoid neoplasms: a potential diagnostic pitfall

SATB2 can be used as an immunohistochemical marker for osteoblastic differentiation. The differential diagnosis of a cutaneous sarcomatoid neoplasm sometimes includes osteosarcoma when the tumour concomitantly involves the skin, soft tissue, and bone, or when there is a past medical history of osteosarcoma. As the utility of SATB2 immunohistochemistry in these scenarios was unclear, we aimed to determine the frequency and the pattern of SATB2 expression in a variety of cutaneous sarcomatoid neoplasms. SATB2 expression by immunohistochemistry was evaluated by intensity (0-3) and extent (0-100%) of staining to generate an h-score for each case. Expression levels were classified into high-positive (h-score ≥100), low-positive (20-99), and negative (<20) groups. Positive SATB2 expression was observed in 18/23 (78%) atypical fibroxanthomas (AFX), 10/19 (53%) pleomorphic dermal sarcomas, 9/20 (45%) cutaneous sarcomatoid squamous cell carcinomas, 14/39 (36%) sarcomatoid melanomas, 2/13 (15%) poorly differentiated cutaneous angiosarcomas, 10/17 (59%) high-grade cutaneous leiomyosarcomas, and 7/8 (88%) osteosarcoma controls. With the exception of AFX, all cutaneous neoplasms showed significantly lower average h-scores than osteosarcoma. AFX gave the highest average h-score (71) and percentage of high-positive cases (48%) among all examined cutaneous neoplasms. Only two (1.5%) of all cutaneous cases showed strong intensity of staining. Common SATB2 expression in various cutaneous sarcomatoid neoplasms poses a potential diagnostic pitfall when the differential diagnosis includes osteosarcoma. Requirement of strong staining and a high-positive h-score improves the specificity of SATB2 in differentiating these tumours from osteosarcoma.

Society for Immunotherapy of Cancer (SITC) clinical practice guideline on immunotherapy for the treatment of nonmelanoma skin cancer

Nonmelanoma skin cancers (NMSCs) are some of the most commonly diagnosed malignancies. In general, early-stage NMSCs have favorable outcomes; however, a small subset of patients develop resistant, advanced, or metastatic disease, or aggressive subtypes that are more challenging to treat successfully. Recently, immune checkpoint inhibitors (ICIs) have been approved by the US Food and Drug Administration (FDA) for the treatment of Merkel cell carcinoma (MCC), cutaneous squamous cell carcinoma (CSCC), and basal cell carcinoma (BCC). Although ICIs have demonstrated activity against NMSCs, the routine clinical use of these agents may be more challenging due to a number of factors including the lack of predictive biomarkers, the need to consider special patient populations, the management of toxicity, and the assessment of atypical responses. With the goal of improving patient care by providing expert guidance to the oncology community, the Society for Immunotherapy of Cancer (SITC) convened a multidisciplinary panel of experts to develop a clinical practice guideline (CPG). The expert panel drew on the published literature as well as their own clinical experience to develop recommendations for healthcare professionals on important aspects of immunotherapeutic treatment for NMSCs, including staging, biomarker testing, patient selection, therapy selection, post-treatment response evaluation and surveillance, and patient quality of life (QOL) considerations, among others. The evidence- and consensus-based recommendations in this CPG are intended to provide guidance to cancer care professionals treating patients with NMSCs.

p63 expression in Merkel cell carcinoma: comparative immunohistochemistry invokes TAp63 as the dominant isoform involved

The literature suggests that p63 expression in Merkel cell carcinoma (MCC) is associated with a poor prognosis. p63 immunohistochemistry marks the 2 main isoforms of this transcriptional protein: TAp63 (tumor suppressor-like properties) and ∆Np63 (oncogenic properties). Little information about the isoform of relevance in MCC exists. p40 immunohistochemistry specifically marks ∆Np63, and using comparative, semiquantitative expression of p63 and p40, we sought to clarify the issue. Our cohort of 53 cases (28 men and 25 women, median age 79 years, interquartile range 71-88) was stratified by morphology and viral status. Immunohistochemistry (p63, p40, and cytokeratin 5/6) was performed, H-scores for nuclear expression of p63 and p40 were derived (2 observers; positivity ≥ 10), and interobserver agreement was evaluated. Clinical, pathological, and outcome data were documented. The results were analyzed statistically. Mortality amounted to 57% (median follow-up 686 days, interquartile range 292-1599). Positivity for Merkel cell polyomavirus was observed in 29 (55%) of cases. Expression of p63 and p40 was present in 36 (69%) and 4 (8%) of cases, respectively. Increased age (P = .0241), negative Merkel cell polyomavirus status (P = .0185), and p63 positivity (P = .0012) were significantly associated with mortality. The latter 2 variables were highly correlated (P = .004). The interclass correlation between the 2 sets of H-scores was 0.95. Our findings support an association between p63 expression and reduced overall survival in MCC and show consistency in scoring this prognostic parameter. TAp63 is the dominant isoform of the protein involved. The paradoxical tumor suppressor-like activity of this isoform in p63-positive MCCs with reduced overall survival requires further study.

p63 Is a Promising Marker in the Diagnosis of Unusual Skin Cancer

Skin cancer is the most common type of cancer worldwide. Ozone depletion and climate changes might cause a further increase in the incidence rate in the future. Although the early detection of skin cancer enables it to be treated successfully, some tumours can evolve and become more aggressive, especially in the case of melanoma. Therefore, good diagnostic and prognostic markers are needed to ensure correct detection and treatment. Transcription factor p63, a member of the p53 family of proteins, plays an essential role in the development of stratified epithelia such as skin. In this paper, we conduct a comprehensive review of p63 expression in different types of skin cancer and discuss its possible use in the diagnosis and prognosis of cutaneous tumours.

Metastatic Primary Gastric Squamous Cell Carcinoma: An Uncommon Presentation of a Rare Malignancy

Primary gastric squamous cell carcinoma is a very rare disease. A 53-year-old male with history of hypertension, alcoholism, and nicotine abuse presented to the hospital after a syncopal episode. He complained of bloating abdominal pain, early satiety, and poor appetite. A CT of his abdomen and pelvis revealed a gastric mass with diffuse hepatic metastasis. A gastric mass was seen on upper endoscopy and biopsies revealed gastric squamous cell carcinoma. There was no involvement of the esophagus. This case should add to the limited literature and serve as a reminder that while this is a rare malignancy, it must be considered when evaluating a gastric mass.

METTL3 mediated m6A modification plays an oncogenic role in cutaneous squamous cell carcinoma by regulating ΔNp63

The cutaneous squamous cell carcinoma (cSCC) originates from epithelial stem cells through the dysregulation of self-renewal and differentiation. Recent studies have identified methyltransferase-like 3 (METTL3)-mediated N6-methyladenosine (m⁶A) modification as key regulator of fate of stem cells. However, little is known about the functional importance of METTL3 in cSCC. Here, Western blot and immunohistochemistry were used to investigate the METTL3 levels in cSCC tissues. Functional experiments including surface marker detection, Brdu incorporation assay, colony forming assay, m⁶A dot blot and tumor xenograft assay were performed to investigate the properties in cSCC cell lines after METTL3 knock down. The expression of METTL3 was up-regulated in cSCC samples. METTL3 knock down impaired cSCC cell stem-like properties, including colony forming ability in vitro and tumorigenicity in vivo. Furthermore, METTL3 knock down and methylation inhibitor cycloleucine could decrease the m⁶A levels and the expression of ΔNp63 in cSCC. Exogenous expression of ΔNp63 partially restored the cell proliferation of METTL3-knockdown cSCC cells. Therefore, our data indicated the m⁶A methyltransferases METTL3 as a critical gene in regulating tumorigeneis of cSCC.

ΔNp63 promotes abnormal epidermal proliferation in arsenical skin cancers

Arsenic is known to perturb epidermal homeostasis and induce abnormal keratinocyte proliferation, leading to skin carcinogenesis. P63 and its isoforms are essential to regulate epidermal homeostasis. This study aimed to investigate the role of p63 isoforms in abnormal epidermal proliferation induced by arsenic. Using arsenic-induced Bowen's disease (As-BD; an intraepidermal carcinoma) as a disease model, we found that in As-BD, the expression of proliferating basal keratinocytes marker cytokeratin 14 (CK14) and N-terminal truncated p63 isoform (ΔNp63; proliferation regulator) was increased, however, that of the differentiation marker cytokeratin 10 (CK10) and full-length p63 isoform (TAp63; differentiation regulator) was decreased in squamous cells as compared with healthy subjects. These observations were recapitulated in the arsenic-treated skin equivalents (SEs). The SEs showed that arsenic increased epidermal thickness, induced abnormal proliferation, and increased ΔNp63 expression in squamous cells as compared with the control. Treatment of cultured normal human epidermal keratinocytes (HKCs) with arsenic increased CK14 and △Np63 expressions, but decreased TAp63 and CK10 expressions. Furthermore, knockdown of ΔNp63 by RNA interference abrogated arsenic-induced CK14 expression and recovered the reduction of TAp63 and CK10 caused by arsenic. These findings indicated that ΔNp63 is a pivotal regulator in the abnormal cell proliferation in arsenical cancers.

Cutaneous Squamous Cell Carcinoma: Review of the Eighth Edition of the American Joint Committee on Cancer Staging Guidelines, Prognostic Factors, and Histopathologic Variants

Cutaneous squamous cell carcinoma is the second most common form of nonmelanoma skin cancer after basal cell carcinoma and accounts for the majority of nonmelanoma skin cancer-related deaths. In 2017, the American Joint Committee on Cancer revised the staging guidelines of cutaneous squamous cell carcinoma to reflect recent evidence concerning high-risk clinicopathologic features. This update reviews the literature on prognostic features and staging, including the eighth edition of the American Joint Committee on Cancer Staging Manual. A wide range of histopathologic variants of cutaneous squamous cell carcinoma exists, several of which are associated with aggressive behavior. A review of cutaneous squamous cell carcinoma variants, emphasizing diagnostic pitfalls, immuhistochemical findings and prognostic significance, is included. Of note, the eighth edition of the American Joint Committee on Cancer Staging Manual refers to squamous cell carcinoma of the head and neck only.

Establishment of a Clinic-based Biorepository

The incidence of skin cancer (e.g., squamous cell carcinoma, basal cell carcinoma, and melanoma) has been increasing over the past several years. It is expected that there will be a parallel demand for cutaneous tumor samples for biomedical research studies. Tissue availability, however, is limited due the cost of establishing a biorepository and the lack of protocols available for obtaining clinical samples that do not interfere with clinical operations. A protocol was established to collect and process cutaneous tumor and associated blood and saliva samples that has minimal impact on routine clinical procedures on the date of a Mohs surgery. Tumor samples are collected and processed from patients undergoing their first layer of Mohs surgery for biopsy-proven cutaneous malignancies by the Mohs histotechnologist. Adjacent normal tissue is collected at the time of surgical closure. Additional samples that may be collected are whole-blood and buccal swabs. By utilizing tissue samples that are normally discarded, a biorepository was generated that offers several key advantages by being based in the clinic versus the laboratory setting. These include a wide range of collected samples; access to de-identified patient records, including pathology reports; and, for the typical donor, access to additional samples during follow-up visits.

Challenges in the diagnosis of cutaneous adnexal tumours

The diagnosis of cutaneous adnexal neoplasms, a heterogeneous group of entities, is often perceived by practising pathologists as challenging. A systematic approach to diagnosis is necessary for classification of these lesions, which establishes the tumour differentiation (follicular, sebaceous, sweat gland or apocrine) and evaluates histological features differentiating between benign and malignant entities. Consideration of clinical history is a necessary adjunct in evaluation of the adnexal neoplasm, as characteristic anatomical sites are described for many adnexal lesions. In some instances, immunohistochemical studies may also be employed to aid the diagnosis. The differential diagnosis between primary cutaneous adnexal neoplasms and cutaneous metastases from visceral tumours may also be difficult. Clinical, radiological, histological and immunohistochemical characteristics will be further discussed, considering that the correct diagnosis has a significant impact on the patient's management and prognosis.

Cutaneous metastasis from anaplastic thyroid carcinoma exhibiting exclusively a spindle cell morphology. A case report and review of literature

Anaplastic thyroid carcinoma is a highly aggressive cancer accounting for 1-2% of thyroid malignancies. Cutaneous metastases from anaplastic thyroid carcinoma are exceedingly rare. We report a 65-year-old woman with anaplastic thyroid carcinoma (BRAF V600E mutation) who had lymph node metastases (pT4 N1b) treated by total thyroidectomy, postoperative radiotherapy, adjuvant chemotherapy (paclitaxel and pazopanib) and targeted therapy (vemurafenib). Nine months after initial diagnosis, radiographic studies revealed multiple pulmonary metastases. A dermatologic examination showed a solitary 1.2-cm chest nodule. Skin biopsy from this nodule revealed infiltrative dermal spindle cells arranged in poorly formed fascicles. Immunohistochemical studies demonstrated the tumor cells to be PAX-8 (+), pancytokeratin (+, focally), TTF-1 (-) and SOX-10 (-). Comparison with the patient's primary anaplastic thyroid carcinoma revealed focal areas of poorly differentiated spindle cells morphologically similar to the malignant spindle cells in the skin biopsy. Together, these findings confirmed the diagnosis of anaplastic thyroid carcinoma metastatic to skin. Cutaneous metastasis of anaplastic thyroid carcinoma composed exclusively of spindle cells broadens the histologic differential diagnosis of cutaneous spindle cell malignancies and presents further diagnostic challenges. PAX-8 may be useful in discerning the spindle cell component of anaplastic thyroid carcinoma from other spindle cell malignancies in the skin.

CD109 is a novel marker for squamous cell/adenosquamous carcinomas of the gallbladder

Gallbladder cancer is the most common biliary tract malignancy with the worst overall prognosis. CD109 is a co-receptor of TGF-β1 and suppresses TGF-β signaling. In this study, CD109 protein expression in three subtypes of gallbladder cancer was examined by immunohistochemistry on human tissue samples and tissue microarrays. We found that CD109 is specifically expressed in malignant squamous cells in squamous cell carcinomas (86.7 %) and adenosquamous carcinomas (91.7 %), but not in adenocarcinomas or normal gallbladder tissues. Thus, CD109 may be a potential pathology marker for gallbladder squamous cell/adenosquamous carcinomas.