Pulmonary adenocarcinoma with intestinal-type differentiation

Pulmonary enteric adenocarcinoma: an overview

Most commonly described as sporadic, pulmonary adenocarcinoma with enteric differentiation (PAED) is a rare variant of invasive lung cancer recently established and recognised by the World Health Organization. This tumour is highly heterogeneous and shares several morphological features with pulmonary and colorectal adenocarcinomas. Our objective is to summarise current research on PAED, focusing on its immunohistochemical and molecular features as potential tools for differential diagnosis from colorectal cancer, as well as prognosis definition and therapeutic choice. PAED exhibits an 'entero-like' pathological morphology in more than half cases, expressing at least one of the typical immunohistochemical markers of enteric differentiation, namely CDX2, CK20 or MUC2. For this reason, this malignancy appears often indistinguishable from a colorectal cancer metastasis, making the differential diagnosis laborious. Although standard diagnostic criteria have not been established yet, in the past few years, a number of approaches have been addressed, aimed at defining specific immunohistochemical and molecular signatures. Based on previously published literature, we have collected and analysed molecular and immunohistochemical data on this rare neoplasm, and have described the state of the art on diagnostic criteria as well as major clinical and therapeutic implications.The analysis of data from 295 patients from 58 published articles allowed us to identify the most represented immunohistochemical and molecular markers, as well as major differences between Asian PAEDs and those diagnosed in European/North American countries. The innovative molecular approaches, exploring driver mutations or new gene alterations, could help to identify rare prognostic factors and guide future tailored therapeutic approaches to this rare neoplasm.

Clinicopathological, radiographic, and oncogenic features of primary pulmonary enteric adenocarcinoma in comparison with invasive adenocarcinoma in resection specimens

Primary pulmonary enteric adenocarcinoma (PEAC) is a rare subtype of primary lung adenocarcinoma. However, it is not known whether there are any distinctive clinical or molecular features.PEACs were retrospectively identified in 28 patients from July 2014 to June 2016. We compared the clinicopathological, radiographic, and oncogenic characteristics of PEAC and primary pulmonary invasive adenocarcinoma (IAC).A total of 28 PEAC patients and 92 IAC patients were compared. PEAC occurred more frequently in males (P = .008), in older patients (P = .041), in those with larger lesions (P = .001), and in those in a more advanced stage (P = .011). Radiologically, PEAC patients had larger lesions (P = .025) and more solid (P = .006); however, there were no statistically significant differences in lobulation, spiculation, pleural indentation, pleural effusion, and lymphadenopathy between PEAC and IAC. PEAC had higher values of carcinoembryonic antigen (P = .008) and carbohydrate antigen 19-9 (P < .001) than IAC. PEAC had a higher incidence (40% vs 63%, P < .001) of Kristen rat sarcoma viral oncogene homolog (KRAS) mutations and a lower incidence (10.71% vs 3.3%, P < .001) of epidermal growth factor receptor (EGFR) mutations. Villin may be a useful marker in the differential diagnosis of PEAC. KRAS mutations occurred more frequently in PEACs, which are cytokeratin 7-negative (P = .032). EGFR mutation rates were higher in PEACs, which are cytokeratin 20- and caudal type homeobox transcription factor 2-negative (P = .041).PEAC is a rare and heterogeneous nonsmall-cell lung cancer subgroup with distinctive clinicopathological, radiographic, and molecular features. These results need to be further confirmed in future studies.

Primary pulmonary adenocarcinoma with intestinal differentiation mimicking metastatic colorectal carcinoma: case report and review of literature

Pulmonary adenocarcinoma with intestinal differentiation is rare and typically expresses proteins common to lung primaries. We report a case in a 51-year-old woman with a solitary 3.3-cm mass in the left lower lobe. Additional clinical investigation, including positron emission tomography scan with fluorine 18-labeled fluorodeoxyglucose, colonoscopy, and capsule endoscopy of her small bowel, revealed no evidence of tumor elsewhere. She underwent left lower lobectomy with mediastinal lymphadenectomy. Histologic examination revealed tall columnar cells without goblet cell differentiation arranged in a cribriform and acinar pattern with extensive central necrosis. Metastatic carcinoma was present in multiple hilar lymph nodes. Mediastinal lymph nodes were negative. Immunohistochemical stains demonstrated diffuse positivity for cytokeratin (CK) 20 and CDX-2 in neoplastic cells with negative staining for CK7 and thyroid transcription factor-1. CK7 expression has been documented in all 14 cases previously reported. This is the first description of pulmonary adenocarcinoma with intestinal differentiation with histopathologic and immunophenotypic findings indistinguishable from metastatic colorectal adenocarcinoma.

Pulmonary Adenocarcinomas With Enteric Differentiation

Primary pulmonary adenocarcinomas with enteric differentiation (PAED) are mainly composed of tall-columnar cells that show similarity to intestinal epithelia and colorectal carcinomas. In this study, we analyzed the immunostaining profiles of 7 PAEDs in comparison with 14 metastatic colorectal carcinomas (MCRs) and 30 usual pulmonary adenocarcinomas (PACs), using antibodies against CDX-2, cytokeratin 7 (CK7), cytokeratin 20 (CK20), TTF-1, surfactant apoprotein-A (SP-A), Napsin A, and MUC2. The positive rates for CDX-2, CK7, CK20, TTF-1, SP-A, Napsin A, and MUC2 were 71%, 100%, 43%, 43%, 14%, 0%, and 43%, respectively, in the PAEDs; 100%, 0%, 86%, 0%, 0%, 0%, and 57% in the MCRs; 3%, 100%, 0%, 93%, 73%, 90%, and 0% in PACs. As expected, immunoreactivity of CDX-2, CK20, and MUC2 was detected in PAEDs. The observed decrease or loss of immunoreactivity for TTF-1, SP-A, and Napsin A indicates that these lesions demonstrate a shift away from their pulmonary phenotype, although CK7 expression was retained. The results indicate that CK7 and CK20 may be useful markers for distinction of PAEDs from MCRs.

The Big Eye in the 21st century: the role of electron microscopy in modern diagnostic neuropathology

Electron microscopy (EM) remains a powerful and even essential tool in modern diagnostic neuropathology. tumors are still encountered that defy histological or immunohistochemical classification, and EM can often provide answers in these cases. Tumors of the CNS for which EM is useful include unusual or atypical variants of meningioma, ependymoma, and schwannoma; oligodendroglioma-like tumors composed of small "clear" cells; and small "blue cell" tumors of childhood. EM is of great value in identifying site of origin for metastatic adenocarcinomas of unknown origin-an under-recognized and under-utilized potential for this technique. EM is useful in the diagnosis of peripheral nerve sheath tumors and gastrointestinal autonomic nerve tumors. EM is also important in the evaluation of certain congenital, inherited and metabolic diseases-including ceroid lipofuscinoses, CADASIL syndrome, certain myopathies, and mitochondrial encephalomyopathies--and of certain toxic and drug-induced peripheral neuropathies. An important application of EM is its utility in initiating a workup of an atypical tumor or metabolic condition, for which clinical and histological clues point in no obvious direction. In these situations, EM may provide either an answer outright (including answers to questions not asked) or important clues that guide further workup and narrow the range of diagnostic possibilities.

Immunohistochemical, ultrastructural and molecular study of well differentiated adenocarcinomas of the lung predominantly composed of goblet cells

In order to clarify the morphological and biological characteristics of well differentiated adenocarcinoma of the lung predominantly composed of goblet cells (WDAG), histopathological examinations, including some molecular biological procedures, were carried out using 42 surgical specimens of primary lung carcinoma which were predominantly (>50% of the total cell population) or totally composed of goblet cells. The subjects included 19 men and 21 women, ranging in age from 41 to 81 (mean 60 years old) with predominantly nodular, peripherally located lesions. Ultrastructural examination revealed characteristic apical microvillous filamentous core rootless (AFCR) in some, but not all, cases. Histologically, these AFCR corresponded well with structures stained by phosphotungstic acid hematoxylin (PTAH). The goblet cells of WDAG were divided into PTAH-positive (26 cases) and -negative (16 cases) groups. The PTAH-positive group had larger tumor size, greater number of intrapulmonary and extrapulmonary metastases and shorter disease-free interval. The immunoexpression of p53 protein (60%) and rate of K-ras point mutation (84%) were also higher in the PTAH-positive group. Therefore the goblet cell population of WDAG, though it may appear morphologically homogeneous under light microscopy, is actually composed of heterogeneous groups of cells with different histopathological characteristics and biological behavior.

Lung adenocarcinomas metastatic to the brain with and without ultrastructural evidence of rootlets: an electron microscopic and immunohistochemical study using cytokeratins 7 and 20 and villin

Adenocarcinomas metastatic to brain from lung or colon may pose differentiation difficulties. Ultrastructurally, both may have brush borders with rootlets. This study examines the ultrastructural morphology and immunohistochemical expression of villin (associated with rootlets), cytokeratin 7 (present in lung adenocarcinomas), and cytokeratin 20 (present in colon adenocarcinomas) in 19 formalin-fixed sequential surgical biopsies of lung adenocarcinomas metastatic to brain as compared to 13 colonic adenocarcinoma metastases. Of lung tumor metastases, mucinous differentiation with rootlets was most common [6/19(32%)]. All colon tumor metastases were cytokeratin 7(-), 20(+), and profusely villin(+). Well-formed rootlets were seen. All lung metastases were cytokeratin 7(+) and 20(-). 5/6(83%) lung metastases with rootlets were focally villin(+). 12/13(95%) without rootlets were villin(-). Rootlets are extremely common in lung adenocarcinoma metastatic to brain. Villin immunoreactivity closely correlates with rootlets. Its distribution is a useful adjunct to cytokeratin 7 and 20 in differentiation of lung versus colon adenocarcinomas metastatic to the brain.

Villin, cytokeratin 7, and cytokeratin 20 expression in pulmonary adenocarcinoma with ultrastructural evidence of microvilli with rootlets

Villin (V) is a glycoprotein of microvilli associated with rootlet formation. Most colonic adenocarcinomas have a V positive (+), cytokeratin (CK) 20 (+), CK7-negative (-) immunophenotype; most lung adenocarcinomas have a CK20(-), CK7(+) immunophenotype. The reports of villin immunoreactivity in lung adenocarcinoma range from 6% to 68% in studies using various fixations and varied anti-villin antibodies. Some lung adenocarcinomas have microvilli with rootlets leading to possible diagnostic confusion with metastatic colonic adenocarcinoma to lung. Nine primary lung adenocarcinomas with rootlets on ultrastructure (including four bronchioloalveolar carcinomas [BAC]), four metastatic lung adenocarcinomas with rootlets, nine metastatic colon adenocarcinomas to lung, and 10 randomly selected lung adenocarcinomas without rootlets (including five BAC), were immunostained with monoclonal antibodies to villin (1D2C3), CK7 (OV-TL12/30), and CK20 (Ks20.8) using a streptavidin peroxidase technique with heat-induced epitope retrieval. All primary lung adenocarcinomas with rootlets were CK7(+) CK20(-), and six of nine (67%) were V(+). Cytoplasmic villin positivity occurred in a diffuse--five of nine (56%), focal--two of nine (22%), or brush border pattern--two of nine (22%). Two of four metastatic lung adenocarcinomas with rootlets were V(+). One metastatic lung adenocarcinoma had a CK7(+), CK20(+), V(-) phenotype. All metastatic colonic adenocarcinomas were V(+), CK20(+), CK7(-), and 1 of 10 (10%) lung adenocarcinomas without rootlets was V(+), and all 10 were CK20(-), and CK7(+). In summary, villin positivity is more common in lung adenocarcinoma with rootlets (67%) than those without rootlets (10%). AU primary lung adenocarcinomas were CK7(+), CK20(-). The combination of villin, CK 7, and CK 20 is helpful in differentiating metastatic colon adenocarcinoma from lung adenocarcinoma with rootlets.

Langerhans cell histiocytosis (histiocytosis X) with morphologic expression of desmosomes and microvillous structures

An unusual case of Langerhans cell histiocytosis in a 7-year-old female is presented. She had ultrastructural evidence of desmosomal biogenesis and formation of gland-like structures by lesional cells; their apical plasma membranes were folded into large numbers of microvilli. Despite the presence of these structures characteristic of epithelial cells, an infiltrated plaque on the abdominal skin of this patient was interpreted as cutaneous involvement of multiple system Langerhans cell histiocytosis because the immunohistochemical staining of the lesional cells for CD1a, S100, PNA, CD4, EN-4, and HLA-DR was positive, and numerous Birbeck granules were ultrastructurally identified in some lesional cells. Other clinical data included the presence of scaly erythematous skin lesions on the forehead and lytic osseous lesions in the maxilla, which were also histologically diagnosed as Langerhans cell histiocytosis. The absence of any internal malignancy in this patient readily ruled out the other diagnostic possibility of a metastatic adenocarcinoma showing glandular differentiation with brush border morphogenesis. The possibility that the desmosome-linked lesional epithelioid cells were actually cells of sweat glands entrapped in the histiocytic proliferation was also ruled out. The functional significance of the desmosomes and microvillous structures in the present case of Langerhans cell histiocytosis remains to be clarified. Awareness of this variant of Langerhans cell histiocytosis will be important for averting potential misdiagnosis in favor of epithelial tumors, especially metastatic adenocarcinomas.

Divergent differentiative histogenetic lines in lung tumors: identification of histotypes with pure or mixed ultrastructural phenotype and their prognostic significance

We performed an electron microscopic study of 50 lung tumors, previously diagnosed by light microscopy, and compared the results of the two techniques. Data analysis identified two ultrastructural phenotypes: pure and mixed. The former was characterized by a constant differentiative pattern and the latter by diverging differentiative histogenetic lines. We observed six differentiative lines as follows: squamous, glandular, neuroendocrine, villopodial, intestinal, and apocrine sudoriparous. Features of divergent differentiative lines were observed in 36 cases (64%), throughout the histotypes, sometimes with coexpression of more than one differentiation in a single case and/or cell. Adenocarcinoma was the histotype most frequently observed in pure form whereas most squamous cell carcinomas showed a mixed phenotype. This suggests that the histotype of the different lung tumors arises from a single glandular pluripotent cell, able to differentiate toward divergent differentiative lines. The clinical stage at onset and at the end of the follow-up indicates that the biologic behavior of lung tumors varies according to whether the ultrastructural phenotype is pure or mixed.