Trisomy of chromosome 6 in Merkel cell carcinoma within lymph nodes

Merkel cell carcinoma (MCC) of the skin is a neuroendocrine tumor with characteristic histological and immunohistochemical features. Among various cytogenetic changes, trisomy of chromosome 6 has been reported in 47% of cases using in situ hybridization. Primary tumors, morphologically and immunohistochemically identical to MCCs of the skin, have been described in other organs, including lymph nodes. Here, a cytogenetic study of four cases of MCC of lymph nodes is presented. Four cases of primary MCCs of lymph nodes and ten cases of cutaneous MCCs were studied for chromosome 6 using fluorescent in situ hybridization (FISH). All cases showed typical features of MCC both at hematoxylin and eosin (H&E) and immunohistochemistry. FISH showed trisomy 6 in two out of the four cases of MCCs of lymph node as well as in 6 out 10 cases of MCCs of skin. Lymph nodal and cutaneous MCCs share same histological and immunohistochemical features, as well as same cytogenetic alteration for chromosome 6. It seems that there are more similarities than differences between cutaneous and lymph nodal MCCs. Whether lymph nodal MCCs are primary tumors or metastases from regressed skin lesions is still questionable, although several findings indicate a primary origin.     

Divergent differentiation in endocrine and nonendocrine tumors of the skin

In the skin, endocrine tumors showing areas with nonendocrine features and nonendocrine tumors showing endocrine differentiation are present. (1) Neuroendocrine carcinomas with nonendocrine differentiation: Merkel cell carcinoma (MCC) of the skin has been frequently described in association with squamous cells carcinoma (SCC) which can arise separately (as synchronous or metachronous lesions) from MCC as well as closely intermixed. In the first event the possibility that the lesions are sustained by same causative factors (among which sun exposure is the most probable) is suggested. In cases of lesions closely intermixed the possibility of an origin from a common precursor is suggested. Furthermore, cases of MCC have been described to contain glandular, melanocytic, striated muscle, and lymphoepithelioma-like features. These latter findings further support the hypothesis of tumors showing divergent differentiations. (2) Nonendocrine tumors showing endocrine differentiation: Basal cell carcinoma (BCC) was the first cutaneous nonendocrine tumor described to contain neuroendocrine granules. Presence of endocrine features were subsequently confirmed with immunohistochemical studies. Endocrine features were then described in sweat gland apocrine and eccrine carcinomas. Endocrine elements present in BCC and in sweat gland carcinomas do not show morphological and immunohistochemical features of Merkel cells. Thus the possibility that these tumors develop an immature Merkel cell or a new type of endocrine cell of the skin is suggested. Tumors with follicular differentiation such as trichoblastomas and trichofolliculomas contain a high number of Merkel cells. As Merkel cells are numerous in hair follicles of human fetal skin, the possibility that these tumors recapitulate the human skin embryogenesis is suggested.     

Histologic and immunophenotypic classification of cervical carcinomas by expression of the p53 homologue p63: a study of 250 cases

Recent studies of the p53 homologue p63 indicate that this gene is preferentially expressed in basal and immature cervical squamous epithelium. This study correlated p63 expression with morphologic phenotype and human papillomavirus (HPV) type in a wide range of cervical neoplasms. Two hundred fifty cases of cervical carcinoma, including squamous cell carcinoma (SCCA; n = 178), adenocarcinoma (ADCA; n = 28), adenosquamous carcinoma (ASCA; n = 8), neuroendocrine carcinoma (NECA; n = 15), and other variant or mixed types (n = 21) were studied. Ninety-seven percent of SCCA, 0% of ADCA, and 0% of SCUC showed strong (>75% v <30%) positivity for p63 (P<.001). p63 sharply distinguished SCCA (p63+) from ADCA (p63-), Large-cell, poorly differentiated carcinomas were distinguished as putative glandular (glassy cell) or squamous (lymphoepithelial-like or spindle cell) types based on p63 staining. Eight (73%) of 11 neuroendocrine tumors tested were chromogranin positive; all showed no or low (<30%) levels of p63 immunostaining. Absence of p63 was also associated with a subset of nonneuroendocrine undifferentiated carcinomas. Transitions from squamous to columnar or undifferentiated morphology coincided with loss of p63 expression. A strong association between HPV 16 and p63 positivity was identified because of the colocalization of both within tumors of squamous phenotype. p63 is a powerful marker for squamous differentiation and, when diffusely expressed, excludes a glandular or neuroendocrine differentiation. p63 may be useful for differentiating pure squamous or glandular from adenosquamous carcinomas, tracking shifts in differentiation within tumors, supporting (by its absence) the diagnosis of neuroendocrine carcinomas, and clarifying the spectrum of poorly differentiated carcinomas lacking either squamous or neuroendocrine differentiation.     

Ultrastructural and molecular heterogeneity in non-small cell lung carcinomas: study of 110 cases and review of the literature

The authors reviewed a series of 110 surgical specimens of primary non-small cell lung carcinomas from the Department of Pathology at the Hospital Clinic, University of Barcelona Medical School, between 1987 and 1997. The sample included 25 squamous cell carcinomas, 60 adenocarcinomas, 14 large cell carcinomas, and 11 neuroendocrine tumors. Electron microscopic subcellular characteristics of the lung cancer cells were studied to define the squamous, adenoid, or neuroendocrine differentiation in each tumor. An immunohistochemical study for Cyclin D1 was performed in 96 cases. In 71 cases (65%) the author found a single ultrastructural differentiation, and in 30 cases (27%) ultrastructural differentiation was double: 25 adenosquamous and 5 adeno-neuroendocrine. In 3 cases a triple adeno-squamous-neuroendocrine differentiation was found. There were no cases of squamous-neuroendocrine differentiation. In 6 cases no differentiation of any kind could be found. Cyclin D1 overexpression was found in 58% of all tumors. The positive expression rates in squamous cell carcinoma and adenocarcinoma were 72% and 62%, respectively. In purely adenoid-differentiated tumors there was a strong association between high Cyclin D1 overexpression and differentiation (p=.006). In bronchioloalveolar carcinoma the positivity rate was 70%; all were heavy expressers, compared with 25% of heavy expressers in adenocarcinomas as a whole (p<.005). In purely squamous tumors differentiated ultrastructurally no relationship was found between high Cyclin D1 expression and degree of differentiation (p=.08). Lung cancers are morphologically and molecularly heterogeneous, and certain molecular alterations are related to specific subcellular characteristics.     

Downregulation of BRG-1 repressed expression of CD44s in cervical neuroendocrine carcinoma and adenocarcinoma.

Neuroendocrine carcinomas of the uterine cervix are rare tumors with early metastases, highly aggressive clinical behavior, and poor clinical outcome. Several adhesion molecules like cadherins have been tested in an attempt to explain their unique characteristics. Cluster differentiation 44 (CD44) is a widely expressed cell surface glycoprotein that serves as an adhesion molecule in cell-to-substrate and cell-to-cell interaction. We have examined the expression of the standard CD44 (CD44s) by immunohistochemical stains in the paraffin-embedded cervical neoplasm tissue of 17 cases of primary cervical neuroendocrine carcinoma, 28 cases of cervical adenocarcinoma, and 50 cases of cervical squamous cell carcinoma. Loss of CD44s expression was found in 16 of 17 neuroendocrine carcinomas, 14 of 28 adenocarcinomas, and three of 50 squamous cell carcinomas. The differences were statistically significant. We also examined immunohistochemically the expression of the BRG-1 subunit of the SWI-SNF complex, which has been reported to regulate the expression of CD44 in all cases. Loss of BRG-1 expression was observed in 12/16, 6/14, and 1/3 CD44s-negative neuroendocrine carcinomas, adenocarcinomas, and squamous cell carcinomas, respectively. This study suggests that loss of the CD44s molecule may imply special biological behaviors of cervical neuroendocrine carcinomas, and loss of expression of BRG-1 may contribute to this.     

Molecular pathology and clinicopathologic features of penile tumors: with special reference to analyses of p21 and p53 expression and unusual histologic features.

OBJECTIVES: To examine the histologic features of p21 in penile tumors and to determine the role of p21 and p53 in the pathogenesis of this group of tumors. METHODS: The clinicopathologic features of 87 patients with penile tumors were studied. The expression of p53 and p21 proteins in 49 cases was investigated by immunohistochemistry. RESULTS: Of the 87 tumors studied, 84 represented primary penile tumors (72 malignant and 12 benign) and 3 represented secondary tumors (2 from bladder, 1 from nasopharynx). The primary malignant penile tumors included 66 surface carcinomas with squamous differentiation (92%), 3 cases of Paget disease (4%), 1 case of Bowen disease (1%), and 2 penile urethral squamous cell carcinomas (3%). The former group was subdivided into squamous cell carcinoma (n = 50), verrucous carcinoma (n = 8), basaloid squamous cell carcinoma (n = 3), adenoid squamous cell carcinoma (n = 3), spindle cell carcinoma (n = 1), and adenosquamous carcinoma (n = 1). The benign tumors were squamous cell papillomas (n = 10) and fibromatoses (n = 2). Expression of p21 and p53 was noted in 40% and 89%, respectively, of the 47 patients with primary surface penile carcinoma with squamous differentiation. Positive p21 and p53 expression was also seen in 2 cases of Paget disease. Staining for p21 was often weak and was found in the suprabasal region of carcinomas with squamous differentiation, while p53 expression was seen in the basal region of squamous cell carcinomas. Preinvasive lesions also showed p21 and p53 expression. An inverse correlation between p53 and p21 expression (p53(+)/p21(-) or p53(-)/p21(+)) was noted in half of the squamous cell carcinomas, 4 of 5 verrucous carcinomas, 2 of 3 basaloid squamous cell carcinomas, and in 1 spindle cell carcinoma. The other cases did not show this correlation. CONCLUSIONS: Penile tumors had different histologic variants and p21/p53 expression patterns. Expression of p21 did play a role in some tumors and could be dependent or independent of p53 expression.     

The spectrum of Merkel cell polyomavirus expression in Merkel cell carcinoma, in a variety of cutaneous neoplasms, and in neuroendocrine carcinomas from different anatomical sites

Most Merkel cell carcinomas display pure neuroendocrine differentiation (pure Merkel cell carcinoma), whereas a minority show combined neuroendocrine and nonneuroendocrine elements (combined Merkel cell carcinoma). Recent identification of Merkel cell polyomavirus DNA and Merkel cell polyomavirus large T antigen expression in a proportion of Merkel cell carcinomas has suggested viral-induced oncogenesis. To date, Merkel cell polyomavirus immunohistochemistry has shown an absence of viral large T antigen expression in combined Merkel cell carcinoma as well as select non-Merkel cell carcinoma cutaneous lesions and visceral neuroendocrine tumors. In our series, we aimed to further characterize the frequency and pattern of Merkel cell polyomavirus large T antigen expression by CM2B4 immunohistochemistry in primary and metastatic Merkel cell carcinoma (pure Merkel cell carcinoma and combined Merkel cell carcinoma) and various non-Merkel cell carcinoma lesions from patients with Merkel cell carcinoma, patients without Merkel cell carcinoma, and individuals with altered immune function. Merkel cell polyomavirus large T antigen was detected in 17 (63%) of 27 pure Merkel cell carcinomas and absent in all 15 (0%) combined Merkel cell carcinomas. Furthermore, complete concordance (100%) of Merkel cell polyomavirus large T antigen expression was observed in 10 cases of primary Merkel cell carcinoma and subsequent tumor metastases. We also evaluated 70 non-Merkel cell carcinoma lesions including 15 cases each of pulmonary and gastrointestinal neuroendocrine tumors. All 70 non-Merkel cell carcinoma lesions were negative for Merkel cell polyomavirus by CM2B4 immunohistochemistry, irrespective of any known Merkel cell carcinoma diagnosis and immune status. In summary, our identification of Merkel cell polyomavirus large T antigen expression in a subset of Merkel cell carcinoma and lack of findings in combined Merkel cell carcinomas and non-Merkel cell carcinoma lesions concur with earlier findings and implicate Merkel cell polyomavirus-independent pathogenesis in these cases. Overall, CM2B4 immunohistochemistry appears to be a specific method for Merkel cell polyomavirus detection and has the potential to play an important role in the diagnosis and classification of Merkel cell carcinoma in the future.     

Squamous cell carcinomas arising from adnexal ductal cysts.

Malignant tumors arising from adnexal cysts are rare. We report 2 cases of squamous cell carcinomas that developed within cystic structures arising from adnexal ducts. An in situ hybridization technique for human papillomaviruses (HPV)-6/11, -16, -18, and -31, and immunohistochemical staining for p53 were performed. Both tumors showed focal expression of HPV-16 within areas showing squamoid changes and diffuse expression of p53 within the areas of invasive squamous cell carcinoma. Although nuclear staining for HPV has been identified in tumors of adnexal origin, to our knowledge these are the first cases in which a highly oncogenic HPV subtype, HPV-16, has been identified within squamous cell carcinomas arising from adnexal ductal structures. These cases may help explain primary cutaneous squamous cell carcinomas with no epidermal origin.     

Combined large cell neuroendocrine, small cell and squamous carcinomas of the lung with rhabdoid cells

Two unusual cases of combined lung carcinoma are presented. Both patients, aged 50 and 53 years, had strong histories of cigarette smoking and presented with lung masses. Microscopic examination revealed an uncommon combination of primary lung cancers. Both cases had a dominant histological picture of large cell neuroendocrine carcinoma. The first case was combined with both squamous and small cell carcinomas in almost equal proportions, while the second consisted of large cell neuroendocrine and squamous carcinomas with a focal area of small cell carcinoma. In addition, both cases contained rhabdoid cells. One of the cases pursued an aggressive clinical course with death in 6 months. The other patient presented with recurrent tumor 12 months after the operation and died shortly thereafter. These cases illustrate two examples of uncommon combined lung cancers: large cell neuroendocrine carcinoma combined with squamous carcinoma and small cell carcinoma. An additional feature was the presence of rhabdoid cells in both cases. It is felt that the rhabdoid component is a reflection of de-differentiation or poor differentiation, and may contribute to the aggressive nature of both tumors.     

Prognostic significance of p27Kip1, p45Skp2 and Ki67 expression profiles in Merkel cell carcinoma, extracutaneous small cell carcinoma, and cutaneous squamous cell carcinoma

AIMS: To compare the immunohistochemical expression of prognostic markers p27(Kip1), p45(Skp2) and Ki67 in Merkel cell carcinoma (primary neuroendocrine carcinoma of the skin, MCC), small cell neuroendocrine carcinoma of lung and urinary bladder (SNC), and cutaneous squamous cell carcinoma (SCC). METHODS AND RESULTS: Immunohistochemistry was performed using antibodies directed against p27(Kip1), p45(Skp2) and Ki67 on 72 tumour cases: 24 MCC, 25 SCC, and 23 SNC (15 from the lung and eight from the urinary bladder). Percentages of positive cells were determined for each marker and statistically analysed. Expression profiles on MCC and SCC were significantly different for all three markers. MCC and SNC exhibited significant similarities in their p27(Kip1) and p45(Skp2) expression profiles. In contrast, MCC and SNC differed significantly in their Ki67 proliferation indices, which were much higher in SNC. Additionally, MCC cases showed an association between increased proliferation indices and the appearance of local recurrence(s) and/or metastases. CONCLUSION: The immunohistochemical profile of MCC differs from that of SCC, in spite of their common oncogenesis and the supposed metaplastic origin of MCC, and resembles that of SNC, except for Ki67 levels, which were higher in the latter (characterized by greater biological aggressiveness). High levels of Ki67 also appear to be a prognostic factor in MCC.     

Selective expression of trophoblastic hormones by lung carcinoma: neurendocrine tumors exclusively produce human chorionic gonadotropin alpha-subunit (hCGalpha)

Recent findings suggest that glycoprotein- and protein hormones act as local auto/paracrine growth/differentiation factors in normal and malignant tissue. An imbalanced or even selective production of human chorionic gonadotropin-alpha (hCGalpha) by neuroendocrine tumors in various organs has been reported. In this context, the ectopic production of trophoblastic hormones by lung carcinoma has not been investigated systemically. Because the determination of serum levels of hCGalpha are flawed by a number of factors, we designed an immunohistochemical study to precisely assess the comprehensive paraneoplastic auto-/paracrine hormone production by lung carcinoma of various histological types. To this end, 90 patients with primary lung neoplasms (40 neuroendocrine tumors, 29 adenocarcinomas, 20 squamous cell carcinomas, and 1 adenosquamous carcinoma) were analyzed by our well characterized monoclonal antibodies (mabs) against the glycoprotein hormones hCG, and its derivatives hCGalpha, hCGbeta, hCGbeta core-fragment (hCGbetacf), luteinizing hormone (LH, LHbeta), follicle-stimulating hormone (FSH, FSHbeta), and the protein hormones placental lactogen (PL) and growth hormone (GH). Overall, trophoblastic hormone immunoreactivity was found in 31% (28/90) of all lung carcinomas, regardless of histological differentiation. Detailed analysis showed 23% (21/90) hCGalpha-, 7% (6/90) hCGbeta, and 2% (2/90) hCGbetacf-positive cases. The tumors produced neither the intact heterodimer hCG, nor the other placental protein hormones PL-A/B and GH-V, or the hCG-related pituitary gonadotropins FSH/FSHbeta and LH/LHbeta. With regard to histological differentiation, it appeared that neuroendocrine tumors exclusively produced free hCGalpha in a distinct expression pattern depending on histological tumor grade. Thirty-eight percent (15/40) of all neuroendocrine neoplasms were hCGalpha-positive, and marker positivity increased with more mature, highly differentiated tumors (20% of small cell neuroendocrine carcinomas versus 90% of atypical and typical carcinoids). This is in striking contrast not only to trophoblastic malignancies and testicular germ cell tumors, but also to nontrophoblastic tumors, such as gynecological and urothelial malignancies, 60% of which produce hCGbeta and where marker positivity correlates with poor histological tumor differentiation. In conclusion, free hCGalpha, but not hCGbeta, is a useful marker for neuroendocrine differentiation in primary lung tumors. The fact that it is preferentially produced by the differentiated tumor types (carcinoids) points to a putative biological function in these tissues. The few hCGbeta-positive NSCLC must not be confounded with primary mediastinal choriocarcinoma.     

Non‐urothelial carcinomas of the bladder

Non‐urothelial carcinomas involving the bladder are uncommon and often diagnostically challenging. These carcinomas may show squamous, adenocarcinomatous or neuroendocrine features, with immunohistochemical stains aiding the diagnosis in only a subset of cases. The clinical history in non‐urothelial bladder carcinomas is important, given that the differential diagnosis often includes secondary involvement of the bladder by direct extension or metastasis from carcinomas at other sites. This paper will review non‐urothelial carcinomas in each of these three morphological categories, emphasising recent changes in diagnostic grouping and challenges in the histopathological diagnosis. Review of bladder cancers with squamous morphology will include discussion of conventional squamous cell carcinoma and verrucous carcinoma and their distinction from urothelial carcinoma with extensive squamous differentiation. Bladder carcinomas with adenocarcinomatous change will include primary bladder adenocarcinoma, urachal adenocarcinoma and tumours of Müllerian type. Finally, neuroendocrine neoplasms of the bladder, including well‐differentiated neuroendocrine tumour and neuroendocrine carcinomas, will be discussed. Associated surface findings, risk factors and prognostic features will be described.     

Microtubule-associated protein-2: a new sensitive and specific marker for pulmonary carcinoid tumor and small cell carcinoma.

Microtubule-associated proteins (MAPs) are a major component of cytoskeleton family proteins associated with microtubule assembly. MAP-2 has been shown to be specifically expressed in neuronally differentiated cells. Pulmonary neuroendocrine carcinomas such as carcinoid tumors and small cell carcinomas are derived from neuroendocrine cells. We hypothesize that neuroendocrine cells may also express MAP-2, and therefore, MAP-2 may be used as a marker for pulmonary carcinomas of neuroendocrine differentiation. To investigate the utility of using MAP-2 expression to separate pulmonary neuroendocrine from non-neuroendocrine tumors, we examined the expression of MAP-2 immunohistochemically in 100 cases of pulmonary carcinomas. The immunoperoxidase method with antigen retrieval was used to characterize the expression of MAP-2, chromogranin, synaptophysin, and neuron-specific enolase in 25 small cell carcinomas, 25 carcinoid tumors, 25 adenocarcinomas, and 25 squamous cell carcinomas. All tumors were lung primaries. All 25 cases of carcinoid tumors (100%) as well as 23 of 25 cases (92%) of small cell carcinomas were positive for MAP-2. Four of 25 cases (16%) of adenocarcinomas were positive for MAP-2 and synaptophysin. Among the 25 squamous carcinomas, 4 cases (16%) were positive for MAP-2, 2 cases (8%) were positive for synaptophysin, 11 cases (44%) were positive for neuron-specific enolase, and none was positive for chromogranin. In conclusion, MAP-2 is a new sensitive and specific marker for the pulmonary tumors of neuroendocrine differentiation. We recommend that MAP-2 be added to immunohistochemical panels to separate non-neuroendocrine from neuroendocrine lung tumors.     

An update on diagnostic features of Merkel cell carcinoma

Merkel cell carcinoma (MCC) is an aggressive primary cutaneous neuroendocrine carcinoma that predominantly affects the elderly and immunosuppressed. Although rare, the incidence of MCC is increasing. Evidence suggests that the pathogenesis of MCC is related to Merkel cell polyomavirus infection or ultraviolet mutagenesis. Clinically, MCC typically presents as an asymptomatic violaceous papule on the head and neck. Histologically MCC is a small round blue cell tumor that must be differentiated from other small cell tumors, therefore immunohistochemistry is necessary for diagnosis of MCC. However, recent evidence suggests that some standard diagnostic markers may be less reliable in virus-negative MCC. MCC may develop local and distant metastases, with poor prognosis for advanced disease. Immunotherapy has recently been shown to be effective for many advanced cases. Here, we review diagnostic features of MCC including potential diagnostic and prognostic differences between virus-positive and virus-negative tumors.     

Expression of adhesion molecules and cytokeratin 20 in merkel cell carcinomas

Merkel cell carcinoma (MCC) is an aggressive neuroendocrine carcinoma of the skin. MCCs often show characteristic paranuclear dot-like immunopositivity for cytokeratin 20 (CK20), a globular aggregation of CK20 intermediate filaments. These aggregates typically form rhabdoid features and fibrous bodies and may be associated with a down-regulation in adhesion molecules (AMs). To date, the relationship between the expression of AMs and CK20 and clinicopathological findings in MCC has not been well examined. In this immunohistochemical study, we assessed the expression of AMs, CK20, and chromogranin A (CgA) on MCCs in 8 men and 23 women with this disease, and also characterized their clinicopathological features. This study is the largest of its kind that has been undertaken to date in Japanese patients. Compared to normal tissue, E-cadherin and α- and β-catenins showed reduced membranous expression in 95.7%, 46.7%, and 45.2% of MCCs, respectively. Nuclear E-cadherin localization was seen in four tumors, all of which predominantly showed a CK20 dot pattern. However, there was no significant relationship between the membranous expression of AMs and a CK20 dot pattern. E-cadherin expression was significantly lower in tumors of ≥2 cm, and tumors negative for E-cadherin more frequently developed outside of the head and neck than within those regions. CgA was more intensely expressed in tumors with uniform nuclei and a dense lymphocytic infiltrate than in those that showed pleomorphisms and that had few, if any, infiltrating lymphocytes. These findings suggest that MCCs have a reduced expression of AMs and that down-regulation of E-cadherin expression may correlate with increased tumor aggressiveness. The fact that no significant relationship was demonstrable between the membranous expression of AMs and the CK20 expression pattern suggests that the mechanism of aggregation of intermediate filaments may be different in different types of tumors.     

Primary and metastatic high-grade carcinomas of the salivary glands: A cytologic-histologic correlation study of twenty cases

We reviewed the clinical and fine-needle aspiration (FNA) findings in 20 patients with poorly differentiated carcinomas presenting initially as parotid or as submandibular masses. There were 11 primary tumors and nine metastatic malignancies in 14 males and six females ranging in age from 39 to 89 yr (median = 66). The tumor types included three primary carcinomas with oncocytic features, three additional cases of high-grade parotid carcinoma, one case of primary neuroendocrine carcinoma, two examples of malignant mixed tumor, one high-grade mucoepidermoid carcinoma, and a single example of malignant lymphoepithelial lesion. Six patients with metastatic carcinoma had previous diagnoses of malignancy. In the three remaining individuals, primary carcinomas of the lung (two cases), and an unknown primary site presented initially as parotid masses. Five examples of metastatic squamous cell carcinoma, one metastatic basal cell carcinoma, and two metastatic renal cell carcinomas were identified. One parotid lymphoepithelioma was interpreted cytologically as an atypical lymphoproliferative process suggestive of Hodgkin's disease. Nineteen cases (95%) were correctly classified as carcinoma at the time of FNA. High-grade carcinomas aspirated from the parotid may be primary, but are frequently metastatic to either the gland, or to an intraparotid lymph node. Our experience indicates that some metastatic carcinomas present at this site, without a previous history of malignancy. Distinguishing primary from metastatic lesions has important therapeutic implications. © 1995 Wiley-Liss, Inc.     

Non-endometrioid carcinomas of the uterine corpus: a review of their pathology with emphasis on recent advances and problematic aspects

This review considers the clinical and pathologic features of the various histologic subtypes of endometrial carcinoma excluding those of pure endometrioid type, as the latter tumors were the subject of a previous contribution in the Journal (Vol. 9, No. 2). Non-endometrioid carcinomas, which account for about 10% of endometrial carcinomas, may pose a great array of problems in differential diagnosis, including their distinction not only from benign lesions but also endometrioid carcinoma and various tumors that may secondarily involve the uterine corpus. The most common subtypes are serous, mucinous, and undifferentiated. Rarer tumors are clear cell, squamous, transitional cell carcinomas, and a variety of poorly differentiated carcinomas with unusual forms of differentiation, such as hepatoid carcinoma, carcinomas with trophoblastic elements, and giant cell carcinoma. Mixed carcinomas, which are common, are also discussed, including those with a component of endometrioid carcinoma. The final section deals with endometrial involvement by metastatic tumors, lesions that, albeit rare, are sometimes neglected in the differential diagnosis of endometrial carcinomas. Important aspects emphasized are: (1) The potential for serous carcinoma to be mimicked by various forms of papillary endometrioid carcinoma. (2) The rarity of clear cell carcinoma and the greater frequency of clear cells in endometrioid carcinoma. (3) The frequency of mucinous epithelium in tumors of mixed cell type. (4) The frequency with which neoplastic mucinous epithelium originates from the endometrium. (5) The striking degree of differentiation of some squamous cell carcinomas. (6) The occasional predominance of non-endometrioid carcinomas (especially serous or undifferentiated carcinoma) within malignant mullerian mixed tumors. (7) The spectrum of reactive epithelial changes and other non-neoplastic abnormalities that may mimic serous or clear cell carcinoma.     

Large cell carcinoma of the lung: clinically oriented classification integrating immunohistochemistry and molecular biology

This study aimed at challenging pulmonary large cell carcinoma (LLC) as tumor entity and defining different subgroups according to immunohistochemical and molecular features. Expression of markers specific for glandular (TTF-1, napsin A, cytokeratin 7), squamous cell (p40, p63, cytokeratins 5/6, desmocollin-3), and neuroendocrine (chromogranin, synaptophysin, CD56) differentiation was studied in 121 LCC across their entire histological spectrum also using direct sequencing for epidermal growth factor receptor (EGFR) and v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutations and FISH analysis for ALK gene translocation. Survival was not investigated. All 47 large cell neuroendocrine carcinomas demonstrated a true neuroendocrine cell lineage, whereas all 24 basaloid and both 2 lymphoepithelioma-like carcinomas showed squamous cell markers. Eighteen out of 22 clear cell carcinomas had glandular differentiation, with KRAS mutations being present in 39 % of cases, whereas squamous cell differentiation was present in four cases. Eighteen out of 20 large cell carcinomas, not otherwise specified, had glandular differentiation upon immunohistochemistry, with an exon 21 L858R EGFR mutation in one (5 %) tumor, an exon 2 KRAS mutation in eight (40 %) tumors, and an ALK translocation in one (5 %) tumor, whereas two tumors positive for CK7 and CK5/6 and negative for all other markers were considered adenocarcinoma. All six LCC of rhabdoid type expressed TTF-1 and/or CK7, three of which also harbored KRAS mutations. When positive and negative immunohistochemical staining for these markers was combined, three subsets of LCC emerged exhibiting glandular, squamous, and neuroendocrine differentiation. Molecular alterations were restricted to tumors classified as adenocarcinoma. Stratifying LCC into specific categories using immunohistochemistry and molecular analysis may significantly impact on the choice of therapy.