Jerome B. Taxy

Malignant fibrous histiocytoma. An electron microscopic study.

Sixteen cases of malignant fibrous histiocytoma are presented. Electron microscopy of 15 cases demonstrated fibroblast‐like and mononuclear and multinucleated histiocyte‐like cells. A small capillary was at the center of all storiform areas exmained. Ultrastructural examination can be diagnostically useful within the context of a narrow differential diagnosis by conventional microscopy and the ability, by electron microscopy, to eliminate other mesenchymal cell types. In 13 cases, follow‐up information was available from 18 months to 9 years following histological diagnosis. Five patients are alive and 8 patients have died, including two non‐tumor related deaths. In 3 cases follow‐up was less than 4 months. The biologic behavior of the tumor in this series was generally not related to histopathological parameters. The issue of histogenesis is largely unresolvable. Ultrastructural studies of various types of fibrous histiocytomas, suggesting cells of origin other than histiocytes, give credence to the concept that the histiocyte may represent a morphologic state of a given mesenchymal cell rather than a particular cell type. Cancer 40:254–267, 1977.

Sinonasal undifferentiated carcinoma. An aggressive neoplasm derived from schneiderian epithelium and distinct from olfactory neuroblastoma.

Eight cases of a highly aggressive undifferentiated carcinoma of the nasal cavity and paranasal sinuses are described. The patients, who ranged in age from 30-77 years, had multiple sinonasal symptoms, and each had involvement of the nasal cavity, maxillary antrum, and ethmoid sinus. Six tumors extended into the orbital bones, and five penetrated the cranial cavity. Five patients died of disease from 1 to 41 months after diagnosis (median: 4 months), and three are alive with tumor less than 1 year following diagnosis. Microscopically, the neoplasms formed nests, trabeculae, and sheets containing medium-sized cells with small to moderate amounts of eosinophilic cytoplasm. A high mitotic rate, tumor necrosis, and prominent vascular permeation were characteristic. Seven neoplasms were immunoreactive for cytokeratin, five for epithelial membrane antigen, and four for neuron-specific enolase. Ultrastructurally, occasional small desmosomes and rare membrane-bound, dense-core granules were observed. Sinonasal undifferentiated carcinoma is a distinctive clinicopathologic entity that must be distinguished from other, less aggressive sinonasal neoplasms.

Renal medullary carcinoma : rhabdoid features and the absence of INI1 expression as markers of aggressive behavior

Renal medullary carcinoma is a rare, well-recognized highly aggressive tumor of varied histopathology, which occurs in young patients with sickle cell trait or disease. Rhabdoid elements, occasionally seen in high-grade renal tumors including renal medullary carcinoma, possibly represent a pathologic marker of aggressive behavior. INI1 (hSNF5/SMARCB1/BAF47) is a highly conserved factor in the ATP-dependent chromatin-modifying complex. Loss of this factor in mice results in aggressive rhabdoid tumors or lymphomas. In humans, the loss of INI1 expression has been reported in pediatric renal rhabdoid tumors, central nervous system atypical teratoid/rhabdoid tumors and epithelioid sarcomas, a possible primary soft tissue rhabdoid tumor. This study compares five renal medullary carcinomas with 10 high-grade renal cell carcinomas (five with rhabdoid features), two urothelial carcinomas and two pediatric renal rhabdoid tumors. All five renal medullary carcinomas, irrespective of histopathology, showed complete loss of INI1 expression similar to that seen in pediatric renal rhabdoid tumors. In contrast, all renal cell carcinomas or urothelial carcinomas, including those with histological rhabdoid features, expressed INI1. Clinically, all five of the patients with renal medullary carcinoma and the two patients with rhabdoid tumors presented with extra-renal metastases at the time of diagnosis. This study demonstrates that renal medullary carcinoma and renal rhabdoid tumor share a common molecular/genetic alteration, which is closely linked to their aggressive biological behavior. However, the absence of INI1 expression is not necessarily predictive of rhabdoid histopathology but remains associated with aggressive behavior in renal medullary carcinoma.

Primary small cell carcinoma of the skin

A case of primary small cell carcinoma of the skin is reported. The patient manifested intermittent, rapidly recurrent local disease which responded to irradiation and chemotherapy. There was no evidence of widespread dissemination during the course of the patients illness, which terminated in a probable episode of sepsis due to leukopenia. Electron microscopic examination demonstrated rare clusters of dense‐core („neurosecretory”︁) granules in cytoplasmic processes. Electron microscopic study is necessary in order to distinguish this tumor from other small cell neoplasms. However, detailed clinical investigation is necessary to rule out a possible primary source elsewhere, e.g., lung.

Adenomatoid tumors: A light microscopic, histochemical, and ultrastructural study

The histogenesis of the adenomatoid tumor has been controversial. The clinical, light microscopic, and histochemical features of six cases, with electron microscopy of three cases is presented and compared to previous studies. The histologic diagnosis rests upon recognition of one of three distinctive patterns: plexiform, tubular, or canalicular, or their various admixtures. There is a similarity of these areas with foci of malignant mesotheliomas. Acid mucopolysaccharide (AMPS), a product of both normal and neoplastic mesothelium, was histochemically present in all six cases and in the reported results of five previous studies. This material was at least partially digested by hyaluronidase. Electron microscopic features include microvilli, desmosomes, tonofilaments and tonofilament‐like structures, and dilated intercellular spaces. This agrees with previous studies, which compared normal mesothelium and mesotheliomas with adenomatoid tumors, and gives further support to a mesothelial origin of these tumors.

The Feasibility of Surgical Enucleation for Renal Cell Carcinoma

Although partial nephrectomy for renal cell carcinoma has been recommended for tumors in solitary kidneys, surgical enucleation has been suggested as an alternative form of surgical management in highly selected patients. To verify the efficacy of surgical enucleation the surgical specimens from 16 standard radical nephrectomies were dissected carefully. The tumors were enucleated ex vivo and carefully investigated pathologically. It was possible to enucleate successfully some well circumscribed, low grade tumors but venous invasion, tumor heterogeneity, occult metastatic disease in lymph nodes, satellite tumor nodules in the kidney and extrinsic spread through the renal capsule were features that may not have been appreciated fully in the operating room. Computerized tomography could not always predict which patients were possible enucleation candidates. Partial nephrectomy remains the preferred surgical treatment in a parenchymal-sparing operation rather than simple enucleation.

Electron microscopy in the diagnosis of malignant schwannoma

Fifteen malignant schwannomas were examined by light and electron microscopy. Five tumors arose in patients with neurofibromatosis and five were contiguous with a peripheral nerve (Group I). Five tumors met neither of these generally accepted diagnostic criteria but were light microscopically seen as compatible with malignant schwannoma when examined under light microscope (Group II). In the better differentiated areas of Group I lesions, long, overlapping, tightly packed cytoplasmic processes were parallel to homogeneous flocculent material, occasionally assuming a linear appearance suggesting basal lamina. In Group II, similar cytoplasmic processes were present but the extracellular material was less extensive and had a less obvious relationship to the plasma membrane. In neither group were fine intracytoplasmic filaments prominent. Malignant schwann cells are seldom as ultrastructurally differentiated as their benign counterparts. Nevertheless, within the context of well‐studied light microscopy and the sampling error inherent in ultrastructural examination, electron microscopy can support the diagnosis of malignant schwannoma.

Pregnancy-associated ectopic decidua.

Extrauterine formation of decidua of stromal cells has been well described, particularly in the cervix and ovary. Sporadic reports have documented decidua formation of peritoneal surfaces and lymph nodes as well as ovarian ectopic decidua in pregnant patients. The apparent hormonal mechanism of this phenomenon suggests a relationship to endometriosis. Between 1983 and 1986, tissue from 10 pregnant patients (acquired from nine at cesarean section and from one at appendectomy) demonstrated submesothelial decidua formation in the form of microscopic nodules and diffuse cell arrangements in an edematous stroma. Some cases showed mild chronic inflammation. An intracytoplasmic lipofusin-type pigment was observed in one case. Four cases had diffuse omental involvement: two with small amounts of free peritoneal blood and two with peritoneal adhesions. Three cases were associated with paratubal cysts: two of these occurred in the uterine and appendiceal serosa, respectively, and one case showed involvement of a retroperitoneal lymph node associated with a pheochromocytoma. No specific gross observations were noted at surgery. There was no prior or subsequent evidence of endometriosis. A review of 958 elective tubal ligations performed between 1983 and 1985 demonstrated 52 examples (5.5%) of serosal decidua formation. Ectopic stromal decidua formation in pregnancy is: (a) a physiologic phenomenon related to the possible specialized sensitivity of the superficial coelomic stroma to progesterone; and (b) diffusely distributed in the peritoneum although it is a clinicopathologic process distinct from endometriosis.

Adenocarcinoma of the pancreas in childhood—Report of a case and a review of the english language literature

A case of adenocarcinoma of the head of the pancreas in a 13‐year‐old girl is reported. Some areas simulated an islet cell tumor by light microscopy, but contained numerous eosinophilic granules which were PAS‐positive and diastase resistant. Ultrastructurally, the granules were large (960 μm–3000 μm in diameter) and electron‐dense, resembling zymogen granules. These granules often showed focal to complete degeneration, occassionally being continuous with a myelin figure. The granules of true islet cell tumors are ultrastructurally distinctive and it is urged, therefore, that all pancreatic neoplasms in children be studied by histochemistry and electron microscopy. Carcinoma of the pancreas in childhood is a rare tumor, often with a rapid clinical course resulting in death. Morphologic separation of cases reported in the English language literature can be made on the basis of acinar differentiation. This feature has been suggested as a peculiarity of childhood pancreatic carcinoma. However, there is a suggestion that this phenomenon occurs in a small percentage of adult tumors as well. More extensive morphologic studies in adult pancreatic cancer may be warranted.

The spectrum of olfactory neural tumors. A light-microscopic immunohistochemical and ultrastructural analysis

Twenty-eight malignant olfactory neural tumors representative of the histologic spectrum commonly designated as olfactory neuroblastoma were subdivided into two groups: Group I closely resembling classical neuroblastoma (20 cases), and Group II exhibiting neuroendocrine features (eight cases). Immunohistochemically, the tumors were analyzed by using antibodies to keratin, neurofilament protein, S-100, and neuron specific enolase. Neuron specific enolase was the most consistently positive in both groups. Single S-100 positive cells, within or at the edges of tumor nests, often corresponded ultrastructurally to Schwann cells at the tumor-stroma interface. Keratin and neurofilament proteins were expressed singly or together by a small number of cases in both groups. All 11 tumors examined ultrastructurally exhibited neuronal processes containing dense-core granules. The results indicate the following: (a) the reliable diagnostic utility of electron microscopy; (b) the frequent occurrence of Schwann cells in these tumors despite their inconspicuousness by light microscopy; and (c) the unexpected expression of keratin by tumors in both groups. The single or coexpression of keratin-neurofilament protein may define a subset of these tumors for which the clinical significance is presently unclear.