Giant cell carcinoma of the lung. A light and electron microscopic study

Primary Pulmonary Carcinomas with Spindle and/or Giant Cell Features: A Review with Emphasis in Classification and Pitfalls in Diagnosis

Primary carcinomas of the lung are vastly represented by the conventional types of adenocarcinomas or squamous cell carcinomas. However, there are other types of non-small cell carcinomas that although uncommon represent a meaningful group that often pose a problem not only in diagnosis but also in classification. Spindle cell and/or giant cell carcinomas, although uncommon represent an important group of primary lung carcinomas. Important to highlight is that current criteria are rather ambiguous and likely not up to date, which renders the classification of these tumors somewhat more obscure. In addition, with the daily use of immunohistochemical stains, the classification of these tumors may also pose a different problem in the proper allocation of these tumors. Proper classification is highly important in the selection process that takes place using such material for molecular analysis. The current molecular characteristics of these tumors are limited and lack more in-depth studies and analyses that can provide specific targets for the treatment of patients with these tumors. The current review attempts to highlight the shortcomings in the current classification and definitions of these neoplasms as well as the more current view regarding these tumors when the use of immunohistochemical stains is employed.

Pleomorphic Carcinoma of the Gallbladder: Report of a Case

The authors report a rare case of primary pleomorphic carcinoma of the gallbladder in a 70-year-old woman. A polypoid tumor protruded into the lumen from the fundus of the gallbladder. Characteristic histologic findings Included a general lack of architectural cohesiveness, marked pleomorphism, presence of mononucleated and multinucleated giant cells, extensive necrosis, leukocyte-tumor cell phagocytosis or cannibalism. Immunoreactivity for cytokeratin, carclnoembryonic antigen and epithelial membrane antigen as well as histochemical positivity for mucins demonstrated the epithelial nature of the tumor. The neoplasm behaved aggressively; the patient died of metastases 9 months after the operation.

Annulate Lamellae in a Large Cell Lung Carcinoma Cell Line with High Expression of Tyrosine Kinase Receptor and Proto-Oncogenes

The morphology, karyotype, in vitro growth properties, and expression of tyrosine kinase receptors and proto-oncogenes are reported for a newly established large cell undifferentiated lung carcinoma cell line (RVH-6849). The results were analyzed concomitantly with those for two well-established cell lines from an adenocarcinoma of the lung (A549) and a squamous cell carcinoma (A431). All three cell lines demonstrated common ultrastructural features of epithelial cells, but only RVH-6849 had frequent aggregates of centrioles and annulate lamellae (AL) and was polyploid, having five to seven copies of chromosome 7 by karyotype analysis. All three cell lines expressed transforming growth factor alpha (TGF-alpha), epidermal growth factor receptor (EGFR), c-erb B-2, and c-met genes. RVH-6849 cells, however, expressed the most messenger RNA (mRNA) for TGF-alpha, c-erb B-2, and c-met. Only EGFR mRNA was expressed more in the other two cell lines, especially in A431 cells. AL represent an exaggerated form of the nuclear membrane-pore complex that is found in actively proliferating cells such as germ and some neoplastic cells. AL are suspected to be involved in the deposition or processing of mRNA: The enhanced coexpression of AL and mRNAs of three tyrosine kinase-containing receptors in RVH-6849 cells may represent such a relationship.

Giant cell carcinoma of the lung impact of diagnosis and review of cytological features

Giant cell carcinoma of the lung is a specific type of lung carcinoma characteristically associated with a highly aggressive clinical behavior. This tumor comprises approximately 1-5% of all lung cancers, affecting a similar patient population as other primary pulmonary carcinomas. It is not routinely treated surgically, owing to the fact that it is metastatic at the time of diagnosis. The cytological diagnosis of this entity on aspiration biopsy has an appreciable impact on patient care. We retrospectively examined 15 cases of lung fine-needle aspirates in which a diagnosis of giant cell carcinoma or large cell carcinoma with giant cell features was made. We applied the criteria for cytological diagnosis of giant cell carcinoma previously set forth in the literature. In cases where there is a tissue diagnosis, we compared the results with the corresponding fine-needle aspirates and correlated them with patient survival. Conclusions are made regarding the reliability of the diagnostic criteria of this malignancy.

Giant cell formation in cells exposed to 740 nm and 760 nm optical traps

BACKGROUND AND OBJECTIVE

Optical trapping is becoming a useful and widespread technique for the micromanipulation of cells and organelles. Giant cell formation following optical trapping was studied to detect the potential adverse effects.

STUDY DESIGN/MATERIALS AND METHODS

The nuclei of preselected single CHO cells were exposed to 740 nm and 760 nm laser microbeam generated by a titanium-sapphire tunable laser at 88 and 176 mW and different time exposures. The irradiated single cells were recorded and observed morphologically following exposure. Giant cells were tabulated and photographed.

RESULTS

The irradiated cells either failed to divide, or they underwent nuclear proliferation to form giant cells through endoreduplication.

CONCLUSION

Giant cells were induced by both 740 nm and 760 nm. The frequency of giant cell formation was higher for the longer time exposures and at the higher power densities. The use of an optical etalon to remove intracavity mode beating and high peak powers of the titanium-sapphire laser caused a significant reduction in the formation of giant cells.

Pulmonary giant cell carcinoma: pathological entity or morphological phenotype?

AIMS

To evaluate the morphological spectrum and clinical significance of giant cell carcinoma and to assess the frequency of tumour giant cell production in a consecutive series of primary (non-giant cell) lung tumours.

METHODS AND RESULTS

Forty-six cases of giant cell carcinoma of the lung were collated from two centres over a 12-year period. Giant cell carcinoma was found to be associated with areas of clear cell carcinoma, spindle cell carcinoma and showed trophoblastic differentiation (syncytiotrophoblastic giant cells and beta-human chorionic gonadotrophin immunopositivity) in 57%, 34% and 26% cases, respectively. 'Pure' giant cell carcinoma was identified in five (11%) cases. Eleven of the tumours contained diastase-resistant periodic acid-Schiff positive material and were separately designated as giant cell adenocarcinomas. Areas of squamous cell and neuroendocrine differentiation (as determined by chromogranin A and Leu-7 immunopositivity) were not found. The median survival for giant cell carcinoma (excluding the giant cell adenocarcinomas) was 18 months. Median survival was not adversely affected by the extent of tumour giant cell formation or by the presence of trophoblastic differentiation. Of 200 consecutive non-small cell lung carcinomas, tumour giant cells constituting < 10% of the tumour were identified in 32% of adenocarcinomas and 26% of squamous cell carcinomas.

CONCLUSIONS

The presence of tumour giant cells in lung carcinoma does not, in itself, indicate a more aggressive tumour type, Giant cell carcinoma of the lung does not appear to be a distinct entity but a morphological phenotype expressed by a heterogenous group of tumours. We support and advocate the use of an encompassing term such as 'pleomorphic' or 'anaplastic' carcinoma for those tumours showing no specific differentiation pattern but which express diverse morphological features such as giant cell formation, clear or spindle cell change.

A histopathological and ultrastructural study of eccrine porocarcinoma with special reference to its subtypes

Five cases of eccrine porocarcinoma were studied by light and electron microscopy. Histopathologically, these could be classified into two types; the common and the giant cell type. The common type was characterized by almost uniform medium-sized cuboidal tumour cells and a formation of well-developed intracytoplasmic lumina. A broad diversity of histopathological and ultrastructural features was seen in these tumours. The tumours of the giant cell type consisted of mononuclear polygonal cells and bizarre giant cells. This type was considered to be an undifferentiated form of porocarcinoma.

Giant cell carcinoma of the lung

BACKGROUND

Giant cell carcinoma of the lung has been described as an aggressive tumor characterized by extensive local and distant disease and extremely short survival. In 1981, the World Health Organization defined giant cell carcinoma as a variant of large cell carcinoma. Before then giant cell lung cancer was a descriptive term, but it was not considered a separate entity.

METHODS

The authors retrospectively studied 16 cases of giant cell carcinoma of the lung.

RESULTS

These cases had a prognosis that was not appreciably different from that for lung cancer of other non-small cell histologic types. Of those patients with pathologic Stage I or II at resection, five of nine are alive and disease-free from 20 to 116 months and one has died without evidence of disease at 15 months.

CONCLUSIONS

Based on this series and a review of the literature, there appears to be an increased incidence of both clinical and subclinical gastrointestinal tract involvement in patients with this histology, compared with patients with other non-small cell histologic types. The authors conclude that patients with giant cell carcinoma of the lung have a prognosis similar to that of patients with other non-small cell histologic types, and that clinicians should be aware of the increased incidence of gastrointestinal tract involvement in this disease.

Immunohistochemical features of giant cell carcinoma of the lung: patterns of expression of cytokeratins, vimentin, and the mucinous glycoprotein recognized by monoclonal antibody A-80

Giant cell carcinoma of the lung (GCCL) is an uncommon and extremely aggressive variant of lung cancer. Characteristic microscopic findings include marked pleomorphism, aggregates of mononucleated or multinucleated giant cells (or both), a general lack of architectural cohesiveness, extensive necrosis, and endocytosis by the giant cells. Although the epithelial character of GCCL has been confirmed by a number of studies, controversy persists as to whether it represents a variant of poorly differentiated adenocarcinoma or of squamous carcinoma. Histochemical studies for mucosubstances have yielded variable and conflicting results. This report describes conventionally fixed and processed samples from 10 cases of GCCL studied with a panel of monoclonal antibodies (Mabs) recognizing different cytokeratin polypeptides (AE1, AE3, AE1/AE3 cocktail, and CAM 5.2), vimentin, and Mab A-80, the last of which binds to a mucinous glycoprotein associated with exocrine differentiation. All 10 cases of GCCL reacted with all cytokeratin Mabs; the extent and intensity of the reaction varied notably. All cases stained strongly and diffusely with Mab AE1 and AE1/AE3, the reaction was less extensive and weaker with CAM 5.2. Significantly, 2 cases reacted focally with Mab AE3. Nine cases reacted extensively and intensely with the vimentin Mab, often showing prominent paranuclear globular profiles. All cases reacted with Mab A-80; the reaction was often strong, but the extent was variable. Findings indicate that all GCCL are indeed cytokeratin positive but that most express polypeptides toward the low-molecular weight end of the spectrum; a small subset also expresses heavier polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Orofacial metastasis of pulmonary giant cell carcinoma

A patient was admitted to the hospital with multiple skin nodules of recent origin and signs and symptoms suggestive of acute pulmonary infection. Because one of the skin masses was located overlying the left mandibular body region, the patient was referred to the hospital dentistry clinic for evaluation. Historical, clinical, and radiographic assessments were consistent with reactive lymphadenopathy, and an intraoral excisional biopsy was performed. The biopsy results were indicative of giant cell carcinoma, which was confirmed by biopsy results from a similar skin lesion on the shoulder and by malignant cells recovered in the sputum and pleural fluids. Although this carcinoma has been shown to rarely metastasize to the skin and lymphatics of the neck, this is the first case report of metastasis to facial lymphatics.

Transitional cell carcinoma of the urinary bladder with osteoclast-type giant cells: a report of two cases and review of the literature

We report two transitional cell carcinomas of the urinary bladder containing numerous osteoclast-type giant cells that stained for vimentin and acid phosphatase (with and without tartrate) and were negative for cytokeratin and lysozyme. One tumour, in a 65-year-old man, was composed of papillary transitional cell carcinoma, invasive poorly differentiated carcinoma with a prominent spindle cell component and numerous osteoclast-type giant cells; repeat curettage 2 months later showed no residual tumour. The second tumour occurred in a 75-year-old woman who underwent a radical cystectomy for a deeply invasive transitional cell carcinoma with a spindle and anaplastic giant cell component and areas containing numerous osteoclast-type giant cells. Osteoclast-type giant cells, which appear to be reactive, should be distinguished from the neoplastic giant cells of giant cell carcinoma.

Globular cytoplasmic inclusion bodies in a metastatic hepatocellular carcinoma of the iliac bone

Globular filamentous bodies are one of the well-known inclusion bodies in hepatocellular carcinoma. The article describes a 56-year-old man with an occult hepatocellular carcinoma in whom the first histologic diagnosis was made from a biopsy from bone. Ultrastructural examination showed many globular filamentous bodies similar to Mallory bodies. The ultrastructural findings and the diagnostic value of these filamentous bodies are discussed.

Pleomorphic (giant cell) carcinoma of the intestine. An immunohistochemical and electron microscopic study

Pleomorphic (giant cell) carcinomas have been described in the lungs, thyroid, pancreas, and gallbladder. Two pleomorphic carcinomas of the small bowel and two of the large bowel are presented. On light microscopic study, the carcinomas were solid, without squamous or glandular differentiation. The tumors were composed of the following three cell types: gemistocytic (giant) cells, smaller polygonal cells, and spindle cells, with identical immunohistochemical reactions. A panel of monoclonal and polyclonal antibodies was applied. All tumors were found to coexpress keratin and vimentin. A positive reaction for neuron-specific enolase (NSE) was found in three tumors and a positive reaction for chromogranin was found in one tumor. On electron microscopic study, intracytoplasmic whorls of intermediate filaments were seen in the perinuclear area. Dense core "neurosecretory" granules were rarely seen. Intestinal pleomorphic carcinomas are histologically identical to pulmonary giant cell carcinomas. The prognosis is poor due to early tumor spread, with only a few months of postoperative survival. The pleomorphic carcinomas have some of the differentiation characteristics of carcinoid tumors and are best regarded as poorly differentiated variants of neuroendocrine carcinomas.

Intermediate filament expression in pituitary adenomas

Seventy-five formalin-fixed and 18 alcohol-fixed pituitary adenomas were studied immunohistochemically using antibodies to keratin, vimentin, neurofilaments (NFs), glial fibrillary acidic protein, desmin, actin, S-100 protein and a variety of pituitary hormones. The pituitary adenoma cells were positive for keratin, vimentin and NFs (68 kDa and 160 kDa) and in a few instances there was co-expression of these three types of intermediate filaments (IMFs). The pattern of keratin-specific staining showed diffuse cytoplasmic or patchy paranuclear reactivity and of NF- or vimentin-specific staining showed fibrillar or patchy paranuclear reactivity. The patchy staining seemed to decorate the fibrous body. There was no correlation between the distribution of IMFs and pituitary hormones in pituitary adenomas except that melanocyte-stimulating-hormone-positive reactivity was limited to the NF-positive adenomas. The pattern of IMF staining did not depend on hormone production in adenomas.

Giant cell carcinoma of the lung--immunohistochemical and ultrastructural evidence of dedifferentiation

Ten examples of giant cell carcinoma of the lung were examined by immunohistochemistry for expression of keratin and vimentin intermediate filaments and for epithelial membrane antigen (EMA). Six cases were also examined electron microscopically. Keratin expression and, to a lesser extent, EMA immunoreactivity were reduced in comparison with better differentiated forms of lung carcinoma. Vimentin expression was increased, often taking the form of strong paranuclear staining. This may correspond to dense paranuclear aggregates of intermediate filaments seen ultrastructurally. Desmosomes were absent or sparse in most tumours. We propose that giant cell carcinoma arises by a process of dedifferentiation. The resulting loss of epithelial features gives rise to neoplastic cells which have features in common with some forms of sarcoma.

Malignant rhabdoid skin tumor: an uncommon primary skin neoplasm. Ultrastructural and immunohistochemical analysis

Rhabdomyosarcomatoid renal tumors were initially described as a subset of tumors in the National Wilms Tumor Study that had light microscopic features similar to rhabdomyosarcomas. Subsequent studies failed to reveal evidence of muscle differentiation, thus the genesis of the term "rhabdoid" tumor. Such renal tumors are rapidly lethal. Recent reports suggest the occurrence of tumors with similar morphology in other anatomic sites. We wish to report a primary malignant rhabdoid tumor of the facial skin with detailed immunohistochemical and ultrastructural studies. Vimentin was expressed in the tumor cells, but there was no immunoreactivity for cytokeratins, neurofilaments, muscle actin, synaptophysin, S-100, melanoma antigen HMB-45, epithelial membrane antigen, neuron specific enolase, Leu-7, leucocyte common antigen or lysozyme/alpha-1-antitrypsin. Ultrastructure revealed typical whorled cytoplasmic aggregates of intermediate filaments. These studies along with a literature review reveal the heterogeneous immunohistochemical profiles of these tumors with common morphologic features. While the histogenesis of these tumors remain uncertain, it is necessary to recognize that these aggressive neoplasms may occur primarily in the skin.

Atypical endocrine tumors of the lung: a histologic, ultrastructural, and clinical study of 19 cases

Lung cancers are divided by light microscopic criteria into several categories, but only two categories are recognized clinically--small cell and non-small cell carcinomas. Transmission electron microscopy has revealed unexpected complexity within each category, blurring the distinctions between them. The present study was undertaken to determine the incidence of dense-core, neuroendocrine-type granules in lung tumors diagnosed by light microscopy as non-small cell carcinomas, i.e., atypical endocrine tumors, and the clinical significance of their identification. Of 205 consecutive primary and metastatic lung cancers, 19 (9 per cent) diagnosed as non-small cell carcinomas by light microscopy were seen to contain neuroendocrine-type granules by electron microscopy and thus were reclassified as atypical endocrine tumors of the lung. Staining with silver stains, periodic acid-Schiff (PAS), PAS with diastase digestion, and mucicarmine was positive in 18, 15, 14, and eight of the 19 cases, respectively. Electron microscopy revealed glandular differentiation in 12 cases and tonofilaments in eight cases, although none of the tumors met the criteria for identification as squamous cell carcinomas. Clinically, the cancers appeared to resemble non-small cell carcinoma more closely than small cell carcinoma. Median survival (12 months) and response to combination chemotherapy (22 per cent) were in the range reported for non-small cell carcinoma. There were no complete responses, despite the use in some cases of regimens active against small cell carcinoma. However, one patient, the only one to date so treated, had a dramatic response to streptozotocin/5-fluorouracil, suggesting that, as in metastatic carcinoid, this combination may have value in the treatment of atypical endocrine tumors of the lung.

Giant cell carcinoma of the lung. Clinical and roentgenographic manifestations

Giant cell carcinoma of the lung is an unusual form of pulmonary malignancy that follows an extremely aggressive clinical course. We report the clinical and roentgenographic manifestations of 14 patients with pathologically proven giant cell carcinoma of the lung, and compare our data to other reports in the literature. Our patients often presented with or developed constitutional or nonthoracic symptoms. This neoplasm was characterized by early evidence of widespread metastases. However, extension of tumor to the chest wall was not as frequent in our series as has been previously described. The survival from the time of diagnosis was extremely short. Any hope of successful treatment of this neoplasm depends on prompt, early diagnosis. Pulmonary giant cell carcinoma should be included in the differential diagnosis of large, round or oval, sharply outlined peripheral lung masses.

A high-grade malignancy bronchial mucoepidermoid carcinoma with features of giant cell carcinoma

A high-grade mucoepidermoid carcinoma associated with giant cell carcinoma of the bronchus was found in a 41-year-old man. Light and electron microscopic examinations showed glandular and squamous elements. The histology of the giant cell carcinoma was similar to those of previously reported giant cell carcinomas. It was assumed that the giant cell carcinoma in the present case is the result of transformation of mucoepidermoid carcinoma originating in the bronchial gland.

Giant cell formation in small cell carcinoma of the lung

Four patients with biopsy proven small cell carcinoma of the lung died rapidly following radiotherapy. At autopsy areas of prominent tumor giant cell formation were found at the primary site in all four and in the metastatic sites in three. Giant cell formation in a tumor may be from the development of another tumor, sublethal damage to the original tumor cells or presence of the two components from the outset. The light and electron microscopic appearances of the giant tumor cells and their existence in the nonradiated sites in our cases suggest that small cell carcinoma, as adenocarcinomas and squamous cell carcinomas, may be associated with giant cell carcinoma-like components.

Pathologic findings of transthoracic needle aspiration in the diagnosis of localized pulmonary lesions

The morphologic findings of transthoracic needle aspirations from 239 patients performed between 1968 and 1980 were reviewed. The cytologic diagnoses were unsatisfactory in nine, benign in 69, suspicious in 21, and malignant in 140 cases; they were verified by histologic evidence in one half of the cases and by clinical data in another third. There were 12 false-negative cases and one false-positive. Of the malignant cases, 106 were primary and 33 metastatic tumors. The following were observed: (1) Cellularity is a useful criterion of malignancy; (2) Cell blocks, prepared in 70 cases, were helpful in tumor typing; (3) Primary lung cancers were accurately typed in 89% of cases and oat cell carcinoma was differentiated from the other types of carcinoma; (4) Metastatic lesions could often be separated from primary carcinomas by comparison with previous histologic slides; and (5) Metastatic colonic carcinoma may be distinguished from primary adenocarcinoma by the presence of well-formed glands with elongated nuclei, a clear apical space, and a prominent brush border.

Separation and spread of nuclear fragments ("nucleotesimals") in colonic neoplasms

After multiple fragmentation of neoplastic nuclei into "nucleotesimals," a recently discovered variety of amitosis, some fragments appear to be inflated to full nuclear size; other probably lyse, releasing nucleic acid, which may assist in the synthesis of new cytoplasm around newly formed nuclei. This observation may be useful in elucidating one mechanism of neoplastic growth.

Warthin-Finkeldey-like cells in benign and malignant lymphoid proliferations

Multinucleate giant cells resembling Warthin-Finkeldey cells have been described in various lymphoid disorders. These Warthin-Finkeldey-like cells (WFLC) with as many as 50 nuclei are of three main types: reticular, lymphocyte and intermediary. In reactive lymphoid proliferations (34 cases) WFLC were mainly observed inside germinal centres and to a lesser extent in the interfollicular zones. In neoplastic lymphoid proliferations (33 cases) WFLC were most commonly found in the lymphocytic predominance type of Hodgkin's disease (16/25 cases). All non-Hodgkin's lymphomas (13 cases) in which WFLC were detected proved to be of low grade malignancy (lymphocytic: one case, lymphoplasmacytic-plasmacytoid: six cases; and centroblastic-centrocytic, six cases). They were also found in two cases of angioimmunoblastic lymphadenopathy. Immunoperoxidase and electron microscopic studies could not elucidate the exact histogenesis of these cells, but it is assumed that they are associated with B cell proliferations.

Microfilamentous carcinoid of the thymus: correlation of ultrastructural study with Grimelius stain

We observed a carcinoid of the thymus that was remarkable for the presence of intracytoplasmic inclusions-readily visible by light microscopy-in the majority of tumor cells. The inclusions were best seen in Grimelius-stained preparations, which also revealed argyrophilic granules present within or close to the masses. On electron microscope examination the inclusions were found to be composed of aggregates of filaments, probably of the intermediate type, which were at times accompanied by neurosecretory granules. The observed incompatibility between the presence of such inclusions and a homogeneous distribution of secretory granules in the cytoplasm is suggestive of a dysfunction of intracellular movements. Microfilamentous carcinoids may represent a class of tumor having a pathologic excretory process.

Giant cell tumor ("osteoclastoma") of the pancreas: a tumor of epithelial origin

Carcinomas of the pancreas with giant cells are not rare, but those containing osteoclast-like tumor cells are quite unusual. This report documents a pancreatic neoplasm comprising both easily recognizable well-differentiated adenocarcinoma and osteoclast-like tumor. The literature on the "osteoclastoma" of the pancreas is reviewed. Evidence for its epithelial deviation is supported strongly by the present case.

Ultrastructure of malignant rhabdoid tumor of the kidney. A distinctive renal tumor of children

An unusual and highly malignant childhood renal tumor has been noted among the specimens of the National Wilms' Tumor Study. Prominent nucleoli, PAS positive cytoplasmic inclusions, and light microscopic features suggestive of rhabdomyoblastic differentiation are hallmarks of this tumor. Ultrastructural examination of 11 specimens revealed the filamentous.

Ultrastructural features of large cell carcinoma of the lung with reference to the prognosis of patients

Epon embedded sections of large cell carcinoma of the lung obtained from 26 patients were examined by light and electron microscopy. On an ultrastructural basis this carcinoma was subclassified into four types: squamous, adenosquamous, adenocarcinomatous, and giant cell types. The giant cell carcinoma was regarded as a special type of squamous or undifferentiated carcinoma. Transition between each of these types was clearly demonstrated. Follow-up study revealed that a close correlation existed between these types and the prognosis of the patients, the squamous type showing a better prognosis and the adenosquamous and adenocarcinomatous types exhibiting equally poor prognoses. The giant cell type invariably pursued a fulminant course. It was suggested that each of the types might represent different stages and directions of differentiation of cancer cells originating from the same ancestry. The authors' view favors the Y construct theory concerning the histogenetic pedigree of pulmonary carcinoma.

Metastatic melanoma: the spectrum of ultrastructural morphology

The fine structure of 26 metastatic melanomas, including 13 pigmented and 13 amelanotic tumors, as studied to define ultrastructural criteria for diagnosis. Several important features in addition to melanosome granules were identified. Dendritic cytoplasmic processes were seen in 25 of the 26 cases, cell clusters formed by concentric aggregates of several cells and their processes were present in 18, and microvilli were found on cell surfaces in all cases. The cytoplasm was complex, containing numerous mitochondria, Golgi systems, endoplasmic reticulum, nonspecific filaments, and microtubules. Nuclear morphology was variable. Basement membranes and cell junctions including desmosomes were often encountered, and some melanomas shared features with Schwann cells, including complex membrane interdigitations. All tumors contained melanosomes, although the classic forms were frequently difficult to identify and abnormal variant forms often predominated. Knowledge of the variant melanosome morphology and an understanding of the other fine structural features of malignant melanocytes can help identify those cases that lack classic premelanosome granules.

Intracellular and extracellular fibrillar structures in gastroduodenal endocrine tumors

Sixteen gastroduodenal endocrine tumors have been examined ultrastructurally for the presence of intracellular and extracellular fibrillar material. Intracellular juxtanuclear fibrillar bodies, often with intermingled secretory granules, were observed in one antral, one pyloric, and three duodenal tumors. In the pyloric tumor there were also extracellular fibrillar structures, which, in contrast to the intracellular fibrils, showed a green birefringence after staining with alkaline Congo red indicating the amyloid nature of these fibrils. One endocrine tumor localized to the fundus-corpus contained extracellular fibrillar bodies of a type typical of adenoid cystic carcinoma.

Absence of carcinoembryonic antigen-like material in mesothelioma: an immunohistochemical differentiation from other lung cancers

This study is to examine the potential usefulness of immunohistochemical staining for carcinoembryonic antigen (CEA)-like material in the differential diagnosis of mesotheliomas (12 cases) from other lung cancers (14 cases) that had been previously diagnosed by transmission and scanning electron microscopy and conventional light microscopy. Indirect immunofluorescent staining for CEA was carried out on formalin-fixed paraffin-embedded sections, and the slides were examined under code. All 9 cases of diffuse mesothelioma were negative, and all 12 cases of adenocarcinoma and bronchioloalveolar carcinoma were positive for CEA-like material. Three localized mesotheliomas and a carcinoid tumor were also negative. A squamous cell carcinoma was positive. A positive immunohistochemical result for CEA-like material in lung cancers will raise the possibility of its being of bronchial epithelial origin.

Nuclear fragmentation in colon carcinoma cells

The nuclei of the epithelial cells of well differentiated adenocarcinoma of the large intestine show characteristic appendages, the nucleotesimals, connected with the main nucleus by lamellar bridges. We interpret this phenomenon as being the result of a hitherto unknown type of amitosis that permits rapid cancer growth in spite of a low mitotic index.

Duodenal carcinoid with cytoplasmic whorls of microfilaments

A unique ultrastructural feature in a duodenal carcinoid is described, viz., large juxtanuclear accumulations of microfilaments arranged in whorls. Similar microfilaments are found in the D1 cell of the gastro-entero-pancreatic endocrine system. Apparently identical whorl-like accumulations of filaments have been previously described in bronchial cells of animals treated with nitrosamines and in human giant cell carcinoma of the lung. We suggest that the D1 cell is the cell of origin for the described carcinoid as well as for the above-mentioned tumours of the lung.

The fine structure of large cell undifferentiated carcinoma of the lung. Evidence for its relation to squamous cell carcinomas and adenocarcinomas

The light microscopic diagnosis of large cell undifferentiated carcinoma of the lung is known to be highly subjective and shows poor interobserver reproducibility; the very existence of this tumor as a separate entity has been challenged. The ultrastructure of seven large cell undifferentiated carcinomas was examined in an attempt to determine whether they were merely poorly differentiated adenocarcinomas and squamous cell carcinomas, or actually represented an entirely separate class of tumors. Four large cell undifferentiated carcinomas demonstrated intra- and intercellular lumina and were designated adenocarcinomas. In three cases there were well formed desmosomes with numerous tonofilaments and intercellular bridges. These tumors were classified as squamous cell carcinomas. An eighth tumor metastatic to the abdominal wall also showed the features of squamous carcinoma. In addition, all tumors contained a variable population of primitive cells without identifying features. The large cell undifferentiated carcinomas were compared ultrastructurally with eight cases of poorly differentiated adenocarcinomas and squamous cell carcinomas classified by light microscopy. These tumors were morphologically similar, but contained fewer primitive cells and greater numbers of differentiated cells. Cells with a clear cytoplasm as seen by light microscopy were present in both the large cell undifferentiated and poorly differentiated groups; these cells contained variable amounts of glycogen but were otherwise similar to the nonclear cells. It is suggested that most of the subcategories of large cell undifferentiated carcinoma represent very poorly differentiated adenocarcinomas and squamous carcinomas.

Pleomorphic carcinoma of the pancreas: an analysis of 15 cases

Pleomorphic carcinoma of the pancreas is a well defined histopathological entity characterized by non-cohesive, sarcoma-like growth pattern, and bizarre mono- and multinucleated tumor giant cells with abundant eosinophilic cytoplasm. Fifteen cases are identified in autopsy files of the Department of Pathology, Washington University School of Medicine, which represent 7.1% of all the non-endocrine pancreatic malignancies found at autopsy. Pleomorphic carcinoma is comparable to pancreatic adenocarcinoma in clinical features such as age, sex, and presenting symptoms except that it is more likely to occur in the body and tail of the pancreas, metastases invariably develop, hematogenous spread is more common, and the median survival is worse. Pleomorphic carcinoma could be distinguished from the pancreatic tumors that resemble giant cell tumor of the bone. Differential diagnostic features between it and amelanotic melanoma, hepatocellular carcinoma, choriocarcinoma, pleomorphic liposarcoma, pleomorphic rhabdomyosarcoma, fibroxanthosarcoma, poorly differentiated epidermoid carcinoma, and giant cell carcinomas of the lung and thyroid are discussed.

Metaplastic squamous cell carcinoma of bronchus simulating giant cell tumor of bone

A 57-year-old man underwent a right pneumonectomy for a bronchogenic carcinoma following bronchoscopy and bronchial biopsy. The tumor was a polypoid mass arising from the lower lobe bronchus. Microscopically it was characterized by mononuclear cells mixed with randomly distributed multinucleated giant cells similar to those seen in giant-cell tumor of bone. Also found were portions showing typical squamous cell and spindle cell carcinoma. Based on the light and electron microscopic findings, we suggest that the current case represents a metaplastic squamous carcinoma showing mesenchymal cell differentiation. A hypothesis on the histogenesis of pleomorphic carcinomas was presented. The problems of histological diagnosis generated by such a tumor should be emphasized.

Giant cell tumor of soft parts. An ultrastructural study

The light-microscopic and ultrastructural findings in a case of so-called giant cell tumor of soft parts, localized at the dorsal side of the left foot of a 23-years-old male are described. An amputation of the lower extremity was performed and subsequently chemotherapy with adriamycin was given for 3 months. Despite the histology and cytologic malignant appearance and the evident vascular invasion, already present at the time of the first excision, the last known status 2 years later seems favorable. There are no pathologic lymph nodes in the groins and no signs of metastases on chest X-rays. From the electron-microscope study no definite conclusion can be drawn as regards the histogenesis of this tumor. we feel, as do others, that many of the principal mononuclear tumor cells are poorly differentiated mesenchymal cells. Some of the neoplastic cells, however, show ultrastructural features suggestive of chondro- or osteoblasts (a well-developed r.e.r. containing electron-dense material; multiple Golgi complexes; masses of glycogen; interdigitating cell membrane villi; cytoplasmic filaments; an extracellular amorphous matrix). Some of the larger tumor cells have the submicroscopic aspects of histiocytes as described in osseous, cutaneous, or pulmonary lesions of the histiocytosis X group. As yet undetermined cytoplasmic inclusion bodies constitute another rare observation in our material.