Basaloid Squamous Carcinoma of the Anal Canal With an Adenoid Cystic Pattern

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.

Molecular and immunophenotypic characterization of anal squamous cell carcinoma reveals distinct clinicopathologic groups associated with HPV and TP53 mutation status

Squamous cell carcinoma (SqCC) is the most common malignancy of the anal canal, where it is strongly associated with HPV infection. Characteristic genomic alterations have been identified in anal SqCC, but their clinical significance and correlation with HPV status, pathologic features, and immunohistochemical markers are not well established. We examined the molecular and clinicopathologic features of 96 HPV-positive and 20 HPV-negative anal SqCC. HPV types included 89 with HPV16, 2 combined HPV16/HPV18, and 5 HPV33. HPV-positive cases demonstrated frequent mutations or amplifications in PIK3CA (30%; p = 0.027) or FBXW7 mutations (10%). HPV-negativity was associated with frequent TP53 (53%; p = 0.00001) and CDKN2A (21%; p = 0.0045) mutations. P16 immunohistochemistry was positive in all HPV-positive cases and 3/20 HPV-negative cases (p < 0.0001; sensitivity: 100%; specificity: 85%) and was associated with basaloid morphology (p = 0.0031). Aberrant p53 immunohistochemical staining was 100% sensitive and specific for TP53 mutation (p < 0.0001). By the Kaplan-Meier method, HPV-negativity, aberrant p53 staining, and TP53 mutation were associated with inferior overall survival (OS) (p < 0.0001, p = 0.0103, p = 0.0103, respectively) and inferior recurrence-free survival (p = 0.133, p = 0.0064, and p = 0.0064, respectively). TP53/p53 status stratified survival probability by HPV status (p = 0.013), with HPV-negative/aberrant p53 staining associated with the worst OS, HPV-positive/wild-type p53 with best OS, and HPV-positive/aberrant p53 or HPV-negative/wild-type p53 with intermediate OS. On multivariate analysis HPV status (p = 0.0063), patient age (p = 0.0054), T stage (p = 0.039), and lymph node involvement (p = 0.044) were independently associated with OS. PD-L1 expression (CPS ≥ 1) was seen in 30% of HPV-positive and 40% of HPV-negative cases, and PD-L1 positivity was associated with a trend toward inferior OS within the HPV-negative group (p = 0.064). Our findings suggest that anal SqCC can be subclassified into clinically, pathologically, and molecularly distinct groups based on HPV and TP53 mutation status, and p16 and p53 immunohistochemistry represent a clinically useful method of predicting these prognostic groups.

CYLD mutation characterizes a subset of HPV-positive head and neck squamous cell carcinomas with distinctive genomics and frequent cylindroma-like histologic features

Mutations in the tumor suppressor CYLD, known to be causative of cylindromas, were recently described in a subset of high-risk (hr) HPV-positive head and neck squamous cell carcinomas (HNSCC). Pathologic and genetic characterization of these CYLD-mutant carcinomas, however, remains limited. Here, we investigated whether CYLD mutations characterize a histopathologically and genomically distinct subset of hrHPV-positive HNSCC. Comprehensive genomic profiling via hybrid capture-based DNA sequencing was performed on 703 consecutive head and neck carcinomas with hrHPV sequences, identifying 148 unique cases (21%) harboring CYLD mutations. Clinical data, pathology reports, and histopathology were reviewed. CYLD mutations included homozygous deletions (n = 61/148; 41%), truncations (n = 52; 35%), missense (n = 26; 18%) and splice-site (n = 9; 6%) mutations, and in-frame deletion (n = 1; 1%). Among hrHPV-positive HNSCC, the CYLD-mutant cohort showed substantially lower tumor mutational burden than CYLD-wildtype cases (n = 555) (median 2.6 vs. 4.4 mut/Mb, p < 0.00001) and less frequent alterations in PIK3CA (11% vs. 34%, p < 0.0001), KMT2D (1% vs. 16%, p < 0.0001), and FBXW7 (3% vs. 11%, p = 0.0018). Male predominance (94% vs. 87%), median age (58 vs. 60 years), and detection of HPV16 (95% vs. 89%) were similar. On available histopathology, 70% of CYLD-mutant HNSCC (98/141 cases) contained hyalinized material, consistent with basement membrane inclusions, within crowded aggregates of tumor cells. Only 7% of CYLD-wildtype cases demonstrated this distinctive pattern (p < 0.0001). Histopathologic patterns of CYLD-mutant HNSCC lacking basement membrane inclusions included nonkeratinizing (n = 22, 16%), predominantly nonkeratinizing (nonkeratinizing SCC with focal maturation; n = 10, 7%), and keratinizing (n = 11, 8%) patterns. The latter two groups showed significantly higher frequency of PTEN alterations compared with other CYLD-mutant cases (38% [8/21] vs. 7% [8/120], p = 0.0004). Within our cohort of hrHPV-positive HNSCCs, CYLD mutations were frequent (21%) and demonstrated distinctive clinical, histopathologic, and genomic features that may inform future study of prognosis and treatment.

CYLD-mutant cylindroma-like basaloid carcinoma of the anus: a genetically and morphologically distinct class of HPV-related anal carcinoma

Rare reports of anal carcinoma (AC) describe histologic resemblance to cutaneous cylindroma, but mutations in the tumor suppressor CYLD, the gene responsible for familial and sporadic cylindromas, have not been systematically investigated in AC. Here, we investigate CYLD-mutant AC, focusing on molecular correlates of distinct histopathology. Comprehensive genomic profiling (hybrid-capture-based DNA sequencing) was performed on 574 ACs, of which 75 unique cases (13%) harbored a CYLD mutation. Clinical data, pathology reports, and histopathology were reviewed for each CYLD-mutant case. The spectrum of CYLD mutations included truncating (n = 50; 67%), homozygous deletion (n = 10; 13%), missense (n = 16; 21%), and splice-site (n = 3; 4%) events. Compared with CYLD-wildtype AC (n = 499), CYLD-mutant ACs were significantly enriched for females (88% vs. 67%, p = 0.0001), slightly younger (median age 59 vs. 61 years, p = 0.047), and included near-universal detection of high-risk HPV sequences (97% vs. 88%, p = 0.014), predominantly HPV16 (96%). The CYLD-mutant cohort also showed significantly lower tumor mutational burden (TMB; median 2.6 vs. 5.2 mut/Mb, p < 0.00001) and less frequent alterations in PIK3CA (13% vs. 31%, p = 0.0015). On histopathologic examination, 73% of CYLD-mutant AC (55/75 cases) showed a striking cylindroma-like histomorphology, composed of aggregates of basaloid cells surrounded by thickened basement membranes and containing characteristic hyaline globules, while only 8% of CYLD-wildtype tumors (n = 34/409) contained cylindroma-like hyaline globules (p < 0.0001). CYLD-mutant carcinomas with cylindroma-like histomorphology (n = 55) showed significantly lower TMB compared with CYLD-mutant cases showing basaloid histology without the distinctive hyaline globules (n = 14) (median 1.7 vs. 4.4 mut/Mb, p = 0.0058). Only five CYLD-mutant cases (7%) showed nonbasaloid conventional squamous cell carcinoma histology (median TMB = 5.2 mut/Mb), and a single CYLD-mutant case showed transitional cell carcinoma-like histology. Within our cohort of ACs, CYLD mutations characterize a surprisingly large subset (13%), with distinct clinical and genomic features and, predominantly, a striking cylindroma-like histopathology, representing a genotype-phenotype correlation which may assist in classification of AC.

Basaloid squamous cell carcinoma of the breast

Basaloid squamous cell carcinoma (BSCC) is a subtype of squamous cell carcinoma that characteristically occurs in the head and neck, may be related to HPV infection and is usually considered to be aggressive. We present the first description of BSCC of the breast. The tumor exhibited characteristic histologic features of BSCC, including nests of basaloid squamous cells with comedonecrosis, abrupt keratinization, and abundant hyaline basement membrane-like material deposition. The tumor showed immunohistochemical features of triple negativity, diffuse p63 positivity, p16 positivity, and Rb negativity. HPV immunogenotyping was negative. The patient was free of disease after treatment with breast conserving surgery, chemotherapy and radiotherapy. BSCC of the breast should be distinguished from basaloid adenoid cystic carcinoma, triple-negative basal-like breast cancer and nonbasaloid squamous cell carcinoma of the breast based on histology and immunohistochemistry. The prognostic implications of BSCC of the breast should be further studied in larger series.

A novel gene expression scoring system for accurate diagnosis of basaloid squamous cell carcinoma of the esophagus

Basaloid squamous cell carcinoma of the esophagus (BSCE) is a rare variant of squamous cell carcinoma that is difficult to distinguish from other carcinomas by preoperative endoscopic biopsy because of its histological varieties. Accurate diagnosis is essential for adequate treatment, and the methods proposed so far (e.g., immunohistochemical staining) have limitations. In this study, we tried to identify the characteristic bundles of gene expression in BSCE using comprehensive gene expression analysis (CGEA). Subsequently, we constructed a gene expression scoring system for the proper diagnosis of BSCE. Fifty-seven surgical specimens, including seven BSCEs, obtained from 30 patients who underwent esophagectomy were used for constructing the scoring system. Three hundred and twelve biopsy specimens, including eight BSCEs, obtained from 80 patients and 20 commercially available formalin-fixed paraffin-embedded (FFPE) specimens diagnosed as esophageal cancer, including 13 BSCEs, were used for validation. After our original mathematical extraction algorithm, 75 genes were extracted to distinguish BSCE from non-BSCE. The cumulative converted values (gene expression score) of the respective 75 genes from each specimen were obtained and lined up in ascending order to assess the optimal gene expression cut-off score for a definitive diagnosis of BSCE. The validation of this scoring system showed high prediction of the biopsy specimens [area under the curve (AUC)=0.981; 95% confidence interval (CI): 0.952‑1.000] and the commercially available FFPE specimens (AUC=0.901; 95% CI: 0.750-1.000). In conclusion, using CGEA in a gene expression scoring system helps in differentiating BSCE from non-BSCE with high accuracy and may contribute in improving BSCE treatment.

Basaloid Squamous Cell Carcinoma of the Anus Revisited

Basaloid squamous cell carcinoma (SCC) of the anus, previously called cloacogenic carcinoma, is a subtype of SCC. There are very few data on the morphologic variation within basaloid SCC of the anus, which may contribute to misdiagnosis. We retrospectively evaluated cases originally diagnosed as basaloid SCC for histologic characterization. We retrieved and reviewed cases of basaloid SCC from 1994 to 2013. Ten (27%) cases were reclassified after review, including basal cell carcinoma (n=6), melanoma (n=2), and neuroendocrine carcinoma (n=2). The final group of basaloid SCC (n=27) showed a female predominance (median age=60 y; range, 42 to 92 y). Morphologically, basaloid SCC could be categorized into 4 groups: transitional carcinoma like (n=10), basaloid with peripheral palisade (n=13), adenoid cystic carcinoma like (n=3), and mucinous microcystic (n=1). In 19 cases the histologic patterns were pure and were mixed in the remainder. CK5/6, p16, and high-risk HPV were positive in all cases (n=27). SOX2 was positive in 18/22 cases. Clinical follow-up was available on 60% of cases; 9 patients (53%) developed local recurrence or metastasis, and 5 (29%) died of disease. Basaloid SCC of the anus is characterized by 4 major histologic patterns and is consistently HPV driven.

Cylindroma-like basaloid anal cancer presenting as a large pelvic mass in a patient with ulcerative colitis

Basaloid cancers of the lower gastrointestinal tract are rare. The lack of mucosal involvement of this type of tumor is uncharacteristic and, to our knowledge, has not been described. In addition, the cylindroma-like appearance of this cancer has only a few examples in the literature. A 51-year-old male presented to us with a history of ulcerative colitis (UC) and obstruction of the anal canal. Imaging and colonoscopy revealed an entirely extraluminal tumor. Percutaneous biopsy yielded a diagnosis of cylindroma-like basaloid carcinoma of the anal region. Neoadjuvant chemotherapy and radiation resulted in stable disease by RECIST criteria. Surgical planning ensued, which led to R0 resection of the tumor, total colectomy and end ileostomy for his UC, and reconstruction of the perineal defect with a rectus myocutaneous flap. Surveillance at 6 months demonstrated no evidence of disease.

Malignant cylindroma in a patient with Brooke-Spiegler syndrome

Malignant cylindroma (cylindromatous carcinoma, cylindrocarcinoma) is the malignant counterpart of benign cylindroma. It is a rare neoplasm, more often developing in the setting of multiple preexisting benign neoplasms. Herein we present an additional case of malignant transformation of the cylindroma diagnosed in an 83-year-old patient with known Brooke-Spiegler syndrome.

Basaloid Squamous Cell Carcinoma of the Sigmoid Colon

Basaloid squamous cell carcinoma (BSCC) of the colon is rarely found proximal to the anal canal. We report a case of an 81-year-old woman who was diagnosed with squamous cell carcinoma (SCC) of the lung without metastasis and BSCC of the sigmoid with differing histologic findings suggesting that these tumors were separate primary neoplasms. SCC of the colon has a dismal prognosis. Surgery is the primary method of treatment when feasible, in addition to chemotherapeutic agents.

Basaloid large cell lung carcinoma presenting as cutaneous metastasis at the colostomy site after abdominoperineal resection for rectal carcinoma

The occurrence of a tumor at the colostomy site after abdominoperineal resection for rectal carcinoma is rare and it may be related to a previously resected carcinoma or another primary tumor. We report a 61-year-old man who developed an ulcerated skin nodule at her colostomy site 6 years after resection of a rectal adenocarcinoma. Histopathologically, the skin nodule was composed of atypical large and pleomorphic cells with high mitotic rate and they were arranged in nests and within lymphatic channels in the dermis. The neoplastic cells were immunoreactive for cytokeratin (CK) AE1/3, CK7, CK34ßE12, epithelial membrane antigen and vimentin while detection of human papillomavirus and Epstein-Barr virus DNA was negative. A diagnosis of basaloid large cell carcinoma of pulmonary origin was suggested and it was confirmed by computed tomography-guided fine needle aspiration of a right subpleural mass. A metastatic tumor at the colostomy site is an exceptional finding and may be the first manifestation of lung cancer, especially if it consist of pleomorphic large cells with high mitotic rate and basaloid immunophenotype.

An update on tumors of the anal canal

CONTEXT

The anal canal possesses complex anatomy and histology and gives rise to a variety of tumor types. Challenging issues remain with regard to both the pathologic diagnosis and the clinical management of these tumors.

OBJECTIVES

To provide an updated overview of the histogenesis, clinical and pathologic characteristics, diagnostic terminology, and relevant clinical management of the various types of anal canal tumors.

DATA SOURCES

Recent literature on clinical and pathologic characteristics of anal canal tumors.

CONCLUSIONS

Although most anal canal tumors are of squamous lineage, a complex variety of other tumors also occurs. Recognition of such diverse tumor entities will allow accurate pathologic diagnosis and most optimal clinical management.

Basaloid (Cloacogenic) Carcinoma Mimicking Intraabdominal Abscess: Report of a Case and Review of the Literature

Cloacogenic carcinoma (CC, basaloid carcinoma) generally occurs around the dentate line, rarely it can arise from the other sides of the colon. There are only 5 cases of CC located outside the anal canal in the literature. The first occurrence of a CC presents as intraabdominal abscess. We describe a 23-year-old male patient who was admitted with fever and severe abdominal pain. Computed tomography imaging showed diffuse wall thickening about 10–11 cm above the rectosigmoid junction, intraabdominal abscess and a soft tissue lession covering the pelvis with a size of 8 × 8.5 cm including cystic necrotic areas. We performed Hartman procedure since the mass was nonresectable. Histopathological examination showed CC. In total, three times radiotherapy and a concurrent three-drug regimen of irinotecan, fluorouracil and folinic acid chemotherapy were administered for 6 weeks. As a result, the patient was lost because of multiple organ dysfunction syndrome that developed 3 months after radio-chemotherapy.

Thymic basaloid carcinoma: a clinicopathologic study of 12 cases, with a general discussion of basaloid carcinoma and its relationship with adenoid cystic carcinoma

Thymic carcinoma (primary carcinoma of the thymic epithelium; type C thymoma) is a rare malignancy. It usually presents in middle-aged to elderly patients and can exhibit a wide variety of morphologic appearances. Thymic basaloid carcinoma (thymic BC) is a particularly rare subtype, with less than 20 cases published in the English literature, mostly in the form of individual case reports. In this study, we present the clinicopathologic and immunohistochemical features of 12 new cases of thymic BC. There were 10 (83%) men and 2 (17%) women. Ages at the time of initial diagnosis ranged from 34 to 77 years (mean 55 y). The 2 most common manners of presentation were dyspnea on exertion (3 patients) and as an incidental finding on radiographic imaging (2 patients). Tumors ranged in size from 4.4 to 17 cm (mean 10.1 cm). One of 12 cases (8.3%) was associated with a multilocular thymic cyst. Immunohistochemistry was performed in 8 cases. Pan-cytokeratin was positive in all cases. CD117 (c-kit) was positive in 6 of 8 cases (75%), p63 was positive in 7 of 8 cases (88%), p53 was positive in 7 of 8 cases (88%), ranging from <10% to 90%, CD5 was focally positive in 3 of 8 cases (38%), collagen type IV was positive in 4 of 8 cases (50%), and proliferative index, as estimated by Ki67, ranged from <1% to approximately 15%. In 1 of 2 cases with sarcomatoid differentiation, Ki67 was greater than 80% in the sarcomatoid area. Cases were negative for thyroid transcription factor-1 (0 of 8), S-100 (0 of 7), and synaptophysin (0 of 7). Long-term data was available in 8 patients with an average follow-up of 30 months. Five patients died of their disease at an average of 34 months from the time of diagnosis. Of the remaining 3 patients, 1 had a stable recurrence and died at 4 years from unrelated causes, and 2 were alive without the evidence of disease at 12 and 7 months, respectively. Thymic BC, although previously regarded as a low-grade neoplasm, has shown that it is capable of aggressive behavior and significant mortality. In this paper, we review the pertinent literature and discuss the possible relationship of thymic BC with thymic adenoid cystic carcinoma, as well as BCs and adenoid cystic carcinomas at other sites.

Morphologic diversity of malignant neoplasms arising in preexisting spiradenoma, cylindroma, and spiradenocylindroma based on the study of 24 cases, sporadic or occurring in the setting of Brooke-Spiegler syndrome

The authors present a series of 24 malignant neoplasms arising in preexisting benign spiradenoma (20), cylindroma (2), and spiradenocylindroma (2). Nineteen patients (12 females, 7 males; age range, 41 to 92 y) had a solitary neoplasm (size range, 2.2 to 17.5 cm; median 4 cm), whereas the remaining 5 (4 females, 1 male; age range, 66 to 72 y) manifested clinical features of Brooke-Spiegler syndrome (BSS), an autosomal dominantly inherited disease characterized by widespread, small, benign neoplasms on which background larger malignant lesions appeared. Microscopically, all cases showed the residuum of a preexisting benign neoplasm. The malignant components of the lesions were variable and could be classified into 4 main patterns, occurring alone or in combination: 1) salivary gland type basal cell adenocarcinoma-like pattern, low-grade (BCAC-LG); 2) salivary gland type basal cell adenocarcinoma-like pattern, high-grade (BCAC-HG); 3) invasive adenocarcinoma, not otherwise specified (IAC-NOS); and 4) sarcomatoid (metaplastic) carcinoma. In 1 case of IAC-NOS, an in situ adenocarcinoma was also found, presumed to have evolved from an adjacent adenomatous and atypical adenomatous component. Cases harboring a sarcomatoid carcinoma featured a malignant epithelial component composed of varying combinations of BCAC-HG, BCAC-LG, IAC-NOS, or squamous cell carcinoma, whereas the sarcomatoid component appeared as either a pleomorphic or spindle-cell sarcoma. Additionally, in 2 cases there were foci of heterologous chondrosarcomatous differentiation and in 1 case there was rhabomyosarcomatous differentiation. Of the 21 patients with available follow-up (range, 3 mo-15 y; average 4.8 y; median 3.5 y), 10 were without evidence of disease, 1 was alive with metastatic disease, 1 was alive with BSS, 3 developed local recurrences, 4 had died of disease, and 2 were dead of other causes. The histologic pattern of the malignant neoplasm correlated to some extent with the clinical course. BCAC-LG neoplasms showed a less aggressive course, with local recurrences but no distant metastases, whereas the BCAC-HG neoplasms typically followed a highly aggressive course resulting in the death 3 of 6 patients with BCAC-HG. Patients with sarcomatoid carcinoma had a relatively good survival. Molecular genetic investigations revealed no mutations in the CYLD gene in the 4 sporadic cases investigated. One patient with BSS revealed a novel missense germline mutation in exon 14 (c. 1961T>A, p. V654E), whereas a living descendant of another deceased patient demonstrated a recurrent nonsense germline mutation in exon 20 (c. 2806C>T, p. R936X). Given the morphologic diversity and complexity of the neoplasms in question, we propose using a more specific terminology with the precise description of the neoplasm components, rather than generic and less informative terms such as "spiradenocarcinoma" or "carcinoma ex cylindroma."

Diagnostic problems in anal pathology

Anal squamous cell carcinoma and its precursor lesions are increasing in incidence in the United States and Europe. This trend predates human immunodeficiency virus/acquired immune deficiency syndrome and has been associated with persistent high-risk human papilloma virus (HPV) genotype infection, previous lower genital tract dysplasia/carcinoma, high frequency anoreceptive intercourse, heavy cigarette smoking, immunosuppression in solid organ transplant and immune disorders, and human immunodeficiency virus seropositivity. Screening protocols for at-risk patients are under active investigation and pathologists are often asked to assess anal canal and perianal biopsies for the presence of dysplasia and/or invasive carcinoma. Because underdiagnosis and overdiagnosis of anal cancer and precancer may lead to inappropriate treatment, it is important for the pathologist to be aware of current screening strategies, specific risk lesions, and the role of pathology in initial diagnosis and evaluation of anal biopsy and/or resection specimens. Standardized histologic criteria and uniform terminology should be used for reporting all anal canal and perianal squamous intraepithelial lesions. HPV subtyping, anal cytology, and recently identified biomarkers, such as p16 and Becton Dickinson ProEx C may provide additional information in problematic cases, but it is important to be aware of the limitations of these assays. HPV has been linked to all the major histologic subtypes of anal carcinoma (eg, basaloid, cloacogenic, transitional, etc.) and this association is strongest for anal canal lesions. With the possible exception of the microcystic pattern, histologic subtype does not seem to predict prognosis; and anal squamous cell carcinomas should be classified as either keratinizing or nonkeratinizing. Poorly differentiated squamous cell carcinomas have a worse prognosis and should be distinguished from poorly differentiated adenocarcinoma, melanoma, and neuroendocrine tumors. Very well differentiated squamous cell carcinoma with pushing margins (so-called giant condyloma of Buschke and Lowenstein) should be classified as verrucous carcinoma; this tumor shows aggressive local infiltration but does not metastasize. As all anal condylomata may harbor foci of high-grade dysplasia or invasive carcinoma, careful sectioning and complete histologic examination is required.

[Anal and anal margin tumors]

Tumors of the anal canal and anal margin are rare. They may raise specific problems for the pathologist. Benign tumors mainly consist of condylomas, cloacogenic polyps and fibro-epithelial polyps. Cancers are infrequent and consisted of well-differentiated squamous cell carcinoma, or poorly differentiated basaloid squamous cell carcinoma. The other malignant tumors are very rare.

Basaloid squamous cell carcinoma of the head and neck: a clinicopathological and follow-up study of 40 cases and review of the literature

Basaloid squamous cell carcinoma (BSCC) is a rare and aggressive variant of cancer that mainly arises in the upper aerodigestive tract. This study reviews the clinico-pathological features and follow-up of a series of cases occurring in the head and neck. During a 32-year period (1974-2005), a total of 40 BSCCs have been diagnosed in the head and neck in our Institution. Males predominated in the series (35M/5F). The average age was 60.2 years (range, 40-85). Tobacco and alcohol consumption was found in more than 80% of the cases. Topographic distribution was as follows: larynx and hypopharynx, 22 cases (55%); oropharynx, 12 cases (30%); and oral cavity 6 cases (15%). The basaloid component predominated in 29 cases (72.5%). Vasculo-lymphatic invasion was detected in 5 cases (12.5%). Lymph node metastases were seen in 25 cases (62.5%, levels II and III in the neck dissection). Local recurrences appeared in 11 cases (27.5%) and distant metastases in 6 (15%). In 7 cases (17.5%) a second primary tumour was detected. The 2002 TNM staging was as follows: Stage I, 5 cases (12.5%); Stage II, 7 cases (17.5%); Stage III, 8 cases (20%), and Stage IV, 20 cases (50%). On follow-up, 21 cases (52.5%) are alive and 19 (47.5%) died of disease. Three- and 5-year overall survival was 50% and 38.5%, respectively. A significant shorter survival was detected in node positive patients (P<0.05).

Thymic tumor with adenoid cystic carcinomalike features: a clinicopathologic study of 4 cases

Thymic carcinomas are rare malignant neoplasms which comprise several histologic subtypes. Adenoid cystic carcinoma (ACC) is included among these subtypes even if it has never been formally reported. We evaluated the clinical, radiologic, morphologic, immunohistochemical, and genetic features of 4 cases of thymic neoplasms with ACC-like features retrieved from the authors' consult files. Most cases affected adult/elderly males (mean 68.5 y; range: 63 to 77 y; M:F ratio=3:1), and were asymptomatic. The clinical history (no evidence of ACC in other sites), radiologic findings (a mass in the thymic region), and morphologic features (residual thymic tissue at the periphery of the neoplasm) strongly supported their primary thymic nature. Grossly, most of the tumors presented as multicystic lesions. On microscopic examination there were true glandular spaces filled with periodic acid-Schiff+material, and pseudocysts containing stromal mucin, collagen IV, and laminin. Features favoring malignancy were overtly infiltrative margins (2/4), mitotic figures (2/4), cytologic atypia (1/4), vascular invasion (1/4), absence of organoid thymuslike pattern (4/4), and absence of immature (TdT+) T lymphocytes (3/3). Necrosis and nerve invasion were not observed. The tumor cells showed the following immunophenotype: p63+(3/3), CK34betaE12+(3/3), CD5+ in scattered cells (1/3), CD117- (3/3), chromogranin-(2/2), synaptophysin-(2/2), and CD56- (2/2). MIB-1 ranged from 1% to 10%. Comparative genomic hybridization revealed an isolated gain of chromosome 8 in 1/3 cases. One patient is alive and well after 20 months, 1 died of another cause 5 years later, and 2 were lost at follow-up. Exceptionally, primary thymic tumors may exhibit histologic features resembling those of ACC of salivary glands. They may be well circumscribed and cytologically bland or invasive and cytologically atypical. In either case they lack an organoid thymuslike pattern and immature T lymphocytes. We have interpreted them as a microscopic subtype of well-differentiated thymic carcinoma of low-grade malignancy, an impression supported by the admittedly limited follow-up information.

Basaloid adenocarcinoma. A new variant of pulmonary adenocarcinoma

The 2004 WHO classification of lung tumours recognised basaloid carcinoma as a variant of squamous and large cell carcinoma. We report a unique case of primary pulmonary adenocarcinoma with a basaloid component. An 82-year-old man underwent pulmonary lobectomy for a 2.8 cm tumour. The patient is disease-free 13 months after diagnosis. Histologically, an invasive carcinoma having a glandular and a solid component was observed. The former was an adenocarcinoma with mucus containing spaces lined by columnar mucinous cells and basaloid cells. The solid component was an organoid proliferation of basaloid-type cells, as in cutaneous basal cell carcinoma. Basaloid cells, but not mucinous cells, were immunoreactive for high molecular weight cytokeratins (CK), CK 7 and, focally, for TTF-1. High Ki67 index, p53 and EGFR expression were also found. This tumour is unique in several respects: (1) The solid areas resemble a conventional basaloid carcinoma, except for the presence of small mucin-containing spaces. (2) The mucinous adenocarcinoma areas contain two layers of columnar and basaloid cells. (3) Both components are neoplastic based on cell morphology, invasive properties and phenotypic profile. These findings indicate that a basaloid variant of adenocarcinoma is also existing in the spectrum of basaloid carcinomas of the lung.