Immunologic and biological properties and clinical significance of placental proteins PP5 and PP12

Among the number of newly isolated placental proteins, PP5 and PP12 share some common characteristics: Both are present in the syncytiotrophoblast of normal placenta and hydatidiform mole, but less frequently, if at all, in choriocarcinoma. The levels in heparinized plasma of both proteins are lower than those in serum, and both are heat-labile. The function of PP12 is completely unknown, whereas PP5 appears to be related to the blood coagulation and fibrinolytic systems at the placental site through its antiplasmin activity. Many exciting avenues of research have been opened to uncover the biological role of these proteins in fetal development and cancer. We are pursuing this research with the immediate goal of assessing the role of PP12 in the blood coagulation system and of studying the expression of both proteins in various forms of cancer.

Immunohistochemical demonstration of relaxin in gynecologic tumors

The immunoperoxidase technique was utilized to study the occurrence and localization of relaxin in malignant and nonmalignant trophoblastic disease and nontrophoblastic gynecologic cancer. Tissue specimens were studied from normal placenta at various weeks of gestation (N = 10), hydatidiform mole (N = 10), invasive mole (N = 10), choriocarcinoma (N = 10), normal endometrium (N = 28), decidua (N = 5), adenocarcinoma of the endocervix (N = 10), of the endometrium (N = 10), corpus luteum (N = 2), ovarian serous papillary cystadenocarcinoma (N = 10), and mucinous cystadenocarcinoma (N = 10). Relaxin was identified in the syncytiotrophoblast of normal placenta at all stages of gestation and also, for the first time, in hydatidiform mole, invasive mole, and choriocarcinoma. No relaxin was found in any nontrophoblastic cancer, including secretory-type adenocarcinoma. The absence of relaxin in the secretory-type endometrial adenocarcinoma is intriguing in light of the finding of relaxin in the normal secretory endometrium. The difference may be due to absence of the relaxin-producing corpus luteum in cancer patients or to loss of relaxin synthesis in the malignant endometrium. The results of this study suggest that relaxin may be synthesized by the normal syncytiotrophoblast and trophoblastic tumors, although differential absorption of relaxin produced in another site cannot be excluded.

Progestin receptor levels in endometria with delayed or incomplete secretory changes

In women with an infertility problem, cytosol progestin receptors were quantified in endometrial biopsies and correlated to histologic postovulatory dating. In 19 women (group A) the histologic dating corresponded to the cycle day; 14 women (group B) showed delayed or incomplete secretory changes. Group B showed significantly lower mean progestin receptor values (132 +/- 22 fmoles/mg protein [+/- SEM, P less than .01] ) than group A (236 +/- 29 fmoles/mg protein). The mean serum progesterone values did not differ significantly between groups A and B in the midluteal or the late luteal phase of the cycle. Inadequate maturation of the endometrium seems to correlate with insufficient development of progestin receptor binding sites rather than with decreased serum progesterone levels.

Immunohistochemical demonstration of relaxin in the genital tract of men

The biotin-avidin immunoperoxidase staining method and antisera against highly purified porcine relaxin were utilized to localize relaxin in the male genital tract. Formalin-fixed tissue specimens from the prostate gland, the testis, epididymis, vas deferens and the seminal vesicle were studied. Specific relaxin immunoactivity was seen in the glandular epithelium of the prostate and also in the glandular epithelium of the seminal vesicle and in the ampullary part of the vas deferens. The testis and epididymis were negative.

Accumulation of prolactin in human seminal vesicles as revealed by immunohistochemical studies

The immunoperoxidase technique was used to identify PRL in human seminal vesicles. PRL reactivity was seen as a strong, specific, perivascular staining in the venous plexuses of the invaginations between the folds in the seminal vesicle walls as well as a diffuse staining in the subepithelial stroma. The immunohistochemical staining methods used in this study do not allow any conclusive speculation on the mechanisms by which high concentrations of PRL in the seminal plasma arise, because no distinct cells could be identified as actively producing and secreting PRL by the current techniques.

Localization of luteinizing hormone, follicle-stimulating hormone, prolactin, and their receptors in human and rat testis using immunohistochemistry and radioreceptor assay

Immunoperoxidase staining and radioreceptor assay were used to study the localization of LH, FSH, and PRL and their receptors in the human and rat testis. In immunohistochemical staining, the Leydig cells of both species were invariably LH positive and generally FSH negative, but there were some FSH positive cells which were morphologically indistinguishable from the Leydig cells. The tubules were LH negative. The Sertoli cells of both species were FSH positive, whereas the spermatogonia and other germ cells were negative. Positive staining for PRL was seen in rat Leydig cells, whereas the human testes were negative. In keeping with the immunohistochemical findings, LH and FSH receptors were found in the testis of both species, but PRL receptors only in the rat. The finding of FSH positive cells in the interstitial tissue may explain why FSH increases the number of Leydig cell LH receptors and increases the sensitivity and maximum response to LH stimulation. Failure to demonstrate PRL and PRL receptors in the human testis indicates either that very low receptor concentrations are needed to bring about PRL action or that the established testicular effects of PRL are indirect.

Immunohistochemical demonstration of relaxin in the genital tract of pregnant and nonpregnant women

The biotin-avidin immunoperoxidase staining method and antisera against highly purified porcine relaxin were used to localize relaxin in the genital tract of pregnant and nonpregnant women. Formalin-fixed tissue specimens from normal placenta, decidua, myometrium, vagina, corpus luteum, and Fallopian tubes were studied. In pregnant women, relaxin was found in the placental syncytiotrophoblast, decidua, and corpus luteum. In nonpregnant women, relaxin was identified in the corpus luteum and endometrium in the secretory, but not in the proliferative, phase. Myometrium, cervix, vagina, and Fallopian tubes were negative for relaxin. This is the first report describing relaxin in the nonpregnant corpus luteum, and we also confirm results of an early disputed study claiming that endometrium in the secretory phase contains relaxin. The origin and biological role of human endometrial relaxin remain to be studied.

Hyperthyroidism and acromegaly caused by a pituitary TSH- and GH-secreting tumour

A female patient with acromegaly, TSH-induced hyperthyroidism and a large eosinophilic pituitary adenoma is reported. Granules in the adenoma cells were by immunohistochemical methods shown to contain GH and with monoclonal TSH-antibodies it was shown that 5-10 per cent of the cells secreted TSH. The basal serum TSH was elevated in the hyperthyroid phases and was not suppressible by exogenous T3 but decreased markedly with dexamethasone. There was a small subnormal rise in serum TSH after TRH injection which was totally suppressed by T3 (but not dexamethasone). L-dopa, bromocriptine and somatostatin caused a 20-30 per cent decrease in serum TSH. The alpha-subunit concentration was also elevated and was equally depressed by bromocriptine and somatostatin. The urinary excretion of TRH was within reference limits. This mixed tumour obviously secreted an excess of both GH and TSH causing acromegaly and hyperthyroidism.

Vaginal polyps with pseudosarcomatous features. A clinicopathologic study of seven cases

Seven cases of vaginal polyps with atypical stromal cells were investigated. Three of the cases were classified as vaginal rhabdomyoma and four as fibroepithelial polyps with atypical stromal cells. All of the patients were adult women with minor or no symptoms. None of the tumor recurred or metastasized. The recognition of the vaginal polyps with bizarre stromal cells is important in order to avoid misdiagnosis of sarcoma, particularly botryoid rhabdomyosarcoma.

Expression of intermediate filaments in ovarian and uterine tumors

We studied the expression of cytoskeletal intermediate filaments in different types of ovarian and uterine sarcomas and carcinomas. In both uterine and ovarian leiomyosarcomas, in endometrial stromal sarcomas, and also in ovarian sarcomas, most tumor cells appeared to be positive for desmin, the muscle type of intermediate filament protein. In most of the tumors, vimentin was present only in some neoplastic cells and in the vascular endothelia. Interestingly, both uterine and ovarian malignant mixed mesodermal tumors appeared to express several types of intermediate filaments, most of the stromal cells being positive for vimentin or desmin, and the epithelial component expressing keratin. The results show that most of the sarcomatous tumors of the ovary and uterus express mainly muscle type of intermediate filament protein. The results also demonstrate the ability of cells of mesodermal origin to express epithelial cytoskeleton markers--cytokeratins.

Pregnancy-specific beta 1-glycoprotein-like material in human cerebrospinal fluid

Human cerebrospinal fluid (CSF) from 34 unselected neurological patients was studied for pregnancy-specific beta 1-glycoprotein (SP1) activity because of the recent finding of SP1 production by cultured glial cells. An organic central nervous system lesion was diagnosed in 9 patients, but not in the other 25. Low levels of SP1 immunoreactivity were found in CSF by RIA, and the adsorption of anti-SP1 antiserum with concentrated CSF abolished the positive immunohistochemical staining of placental tissue obtained with the unadsorbed antiserum. By means of immunoadsorption using monoclonal anti-SP1 antibodies, it was possible to isolate SP1 immunoreactive material from CSF and to demonstrate that it had the same electrophoretic mobility in sodium dodecyl sulfate-polyacrylamide gel electrophoresis as purified placental SP1. These results show that CSF contains SP1-like material that is closely related, if not identical, to placental SP1. The amount of SP1 in CSF has no direct correlation to an organic central nervous system lesion or to abnormality of the CSF.

Immunoperoxidase staining of carcinoembryonic antigen with monoclonal antibodies in adenocarcinoma of the colon

Mouse monoclonal antibodies to carcinoembryogenic antigen (CEA) obtained by the somatic cell hybridization technique of Köhler and Milstein were used in a modified enzyme bridge immunoperoxidase staining method. Both high and low affinity antibodies were tested and their staining properties compared with those of a commercial polyvalent rabbit antiserum. The staining pattern of neoplastic epithelial cells in all seven antibodies in samples of primary adenocarcinoma of the colon was similar, indicating that no gross differences were found in the exposure of the different antigenic determinants of CEA in formalin fixed tissue. The background staining of the monoclonal antibodies are negligible. It is concluded that monoclonal antibodies are superior to conventional antisera in immunoperoxidase staining of CEA.

Immunohistochemical demonstration of placental protein 5 in trophoblastic tumours

An immunoperoxidase technique was used for the detection of placental protein 5 (PP5) in tissue specimens from trophoblastic tumours. PP5 was detected in all of 15 cases of hydatidiform mole, in two out of six destructive moles and in one of seven choriocarcinomas. Though the biological importance of PP5 is not clear, its association with inactivation of plasmin suggests a role in the control of placental invasiveness.

Retrovirus p30-related antigen in human syncytiotrophoblasts and IgG antibodies in cord-blood sera

Sensitive immunological techniques were used to detect retrovirus markers in human pregnancy. A total of 1,540 human cord-blood sera were tested for retrovirus-reactive IgG antibodies using solid-phase enzyme immunoassay and purified RD 114 virus as antigen. Of these, 118 (7.7%) sera were positive. Blocking assays with specific animal anti-p30 sera, use of control antigen, and electrophoretic protein experiments combined with immunological detection indicated that the human antibodies reacted specifically with the p30 protein. The occurrence of antibodies in cord-blood serum had a highly significant correlation to complications during pregnancy and also correlated to the number of previous abortions and stillbirths. When goat anti-RD 114 p30 serum was used in the peroxidase-anti-peroxidase tissue staining procedure, p30-related antigen was detected in sections of all placental specimens (early and term pregnancies, blighted ova, hydatidiform moles, destructive moles and choriocarcinomas). However, in each case only syncytiotrophoblastic cells were positive. These findings, supplemented with different types of blocking tests, lead us to conclude that retrovirus p30-related antigen is selectively expressed in the highly differentiated syncytiotrophoblasts, which in the normal placenta are directly exposed to maternal blood. It is suggested that retrovirus-reactive antibodies may represent an autoimmune-like immune response to the p30-related syncytiotrophoblast antigen escaping during cellular damage.

Immunological evidence for the occurrence of luteinizing hormone-releasing factor and the alpha-subunit of glycoprotein hormones in carcinoid tumors

The immunoperoxidase technique was used to identify LRF and glycoprotein hormones or their subunits in 22 carcinoid tumors of various origins. All tumors were positive for both LRF and the alpha-subunit, whereas stainings with antisera against the beta-subunits of CG, LH, FSH, and TSH were negative. The binding of LRF and the alpha-subunit within the same malignant tissue raises the possibility of a functional relationship between the two.

The use of monoclonal antibodies against human chorionic gonadotropin for immunoperoxidase staining of normal placenta, pituitary gland, and pituitary adenomas

A monoclonal mouse antibody to human chorionic gonadotropin (hCG) was used in a modified unlabeled antibody enzyme-bridge staining method to demonstrate the localization of hCG in normal human placenta, pituitary gland, and six pituitary chromophobe adenomas. Mouse ascitic fluid containing monoclonal antibody could be diluted up to 1:500,000 for detection of hCG in the syncytiotrophoblast, whereas no staining was observed in the pituitary or adenomas even with high antibody concentrations (dilutions from 1:500 upward). Nonspecific background staining was negligible. These results demonstrate that monoclonal antibodies are suitable for immunohistochemical localization of antigens in tissues.

Presence of alpha 2-macroglobulin in normal but not in malignant human syncytiotrophoblasts

alpha 2-Macroglobulin (alpha 2M) was demonstrated in normal syncytiotrophoblasts of both early and full-term human placentas using immunocytological staining. alpha 2M was also detected in hydatidiform moles, the benign tumors of proliferating syncytiotrophoblasts. In contrast, no alpha 2M was detected in invasive moles or choriocarcinomas. In culture conditions, both normal syncytiotrophoblasts and choriocarcinoma cells, identified by production of human chorionic gonadotropin, were negative when stained for alpha 2M or when studied using metabolic labeling and immunoprecipitation or radioimmunoassay. However, alpha 2M was taken up from added human serum by the cultured syncytiotrophoblasts, whereas choriocarcinoma cells remained negative also under these conditions. The possible role of alpha 2M in the regulation of proteolysis in cell invasion is considered.

Serum prolactin levels and immunohistochemical localization of prolactin in trophoblastic disease

The circulating levels of chorionic gonadotropin, pregnancy specific beta-I-glycoprotein, prolactin and oestradiol were estimated by radioimmunoassay in 219 serum samples from 18 patients with choriocarcinoma and 45 samples from 8 patients with hydatidiform mole. Prolactin and oestradiol concentrations were higher in samples which also contained trophoblastic markers. This difference was also seen in patients with choriocarcinoma and it was not due to chemotherapy, since the difference between hCG positive and hCG negative samples was maintained during chemotherapy. Prolactin was found by immunoperoxidase technique in the syncytiotrophoblast of normal placenta throughout gestation, and also in hydatidiform mole, invasive mole and choriocarcinoma. It is suggested that the malignant syncytiotrophoblast may contribute to circulating prolactin levels either by direct secretion of prolactin or by oestrogen stimulation of the pituitary.

Cells from normal brain and gliomas synthesize pregnancy-specific beta 1-glycoprotein-like material in vitro

The synthesis of pregnancy-specific beta 1-glycoprotein (SP1) was studied in normal brain-derived and malignant glial-cell cultures. The normal brain-derived and glioma cells were found to contain SP1 when studied by radioimmunoassay and by the triple-bridge immunoperoxidase technique. The active synthesis of SP1 by these brain-derived cells was confirmed by metabolic labelling and subsequent immune precipitation of the culture medium. The SP1-like material produced by the brain-derived cells had the same molecular weight as purified placental SP1.

Placenta-associated plasma protein-A (PAPP-A, SP4) in trophoblastic tumours

The immunoperoxidase technique was used to study the occurrence of placenta-associated plasma protein A (PAPP-A, SP4) in formalin-fixed paraffin-embedded tissue specimens from 15 hydatidiform moles, 6 invasive moles and 7 choriocarcinomas. PAPP-A was found in the syncytiotrophoblast of all hydatidiform moles, in 5 of the 6 invasive moles and in 6 of the 7 choriocarcinomata. No clinical difference was observed between PAPP-A positive and negative cases of invasive disease.

Pregnancy-specific beta-1-glycoprotein (SP1) in cultured amniotic fluid cells

The synthesis of pregnancy-specific beta-1-glycoprotein (SP1) was studied in amniotic fluid cell cultures using RIA, immunoperoxidase, and immunofluorescence techniques. SP1 was found by RIA in all 11 sonicates and in 21 of 26 culture media. The SP1-immunoreactive material was immunologically similar to maternal serum SP1. Immunoperoxidase and indirect immunofluorescence staining were positive in large cells identified as epithelial amniotic cells by labeling with antikeratin antibodies. Fibroblast-like cells were occasionally found in cultures, but they did not contain demonstrable amounts of SP1. The physiological significance of the findings presented remains unclear.

Steroids in spermatic and peripheral vein blood in testicular feminization

Steroid secretion by the testes in three postpubertal patients with testicular feminization was studied by comparing the steroid concentrations in spermatic and peripheral blood samples obtained prior to gonadectomy. Testosterone, dehydroepiandrosterone (DHEA), and androstenedione were the predominant steroids secreted by these testes. Values for spermatic vein testosterone (60 to 700 nmoles/liter) were lower than those previously reported for normal men, but values for DHEA (20 to 240 nmoles/liter) and androstenedione (30 to 250 nmoles/liter) were within the range found in normal men. The testes of these three patients also secreted pregnenolone, progesterone, 17 alpha-hydroxyprogesterone, dihydrotestosterone, testosterone sulfate, and estradiol. After gonadectomy, the plasma concentration of estradiol declined considerably less than that of testosterone, indicating that estrogen formation from adrenal precursors continued after gonadectomy in these patients.

Identification of luteinizing hormone-releasing factor and alpha subunit of glycoprotein hormones in ductal carcinoma of the mammary gland

The immunoperoxidase technique was used to identify luteinizing hormone-releasing factor (LRF) and the alpha subunit of glycoprotein hormones in ductal carcinoma of the mammary gland. Eleven tumors were studied, using antisera against LRF and alpha subunit, and against the beta subunits of hCG, LH, FSH and TSH. Six of the tumors were both LRF- and alpha-positive and three were negative. One tumour was LRF-positive/alpha-negative, and one was LRF-negative/alpha-positive. None of the anti-beta subunit antisera gave positive staining, and normal breast tissue as well as chronic cystic mastopathy (five cases) were negative with all antisera tested. The results with the anti-alpha and anti-beta subunit antisera suggest that the material stained is free alpha subunit rather than any of the native glycoprotein hormones which share the common alpha subunit.

Immunohistochemical demonstration of luteinizing hormone-releasing factor-like material in human syncytiotrophoblast and trophoblastic tumours

Luteinizing hormone-releasing factor (LRF)-like immunoreactivity was demonstrated by a three layer bridge immunoperoxidase technique in the syncytiotrophoblast of early human placenta, hydatidiform mole and choriocarcinoma. Anti-LRF antiserum was prepared by immunizing rabbits with synthetic LRF coupled to bovine serum albumin (BSA). The immunoreactive site of LRF reacting with the antiserum resided between residues Tyr(5) and Gly(10)-NH2. Syncytiotrophoblast cells of the normal placenta from the first half of pregnancy and trophoblastic tumours, showed staining with anti-LRF antiserum after solid phase immuno-adsorption with Sepharose-coupled BSA. Adjacent control sections showed no staining when prepared with anti-LRF antiserum after immunoadsorption with a Sepharose-coupled LRF-BSA conjugate. The findings of LRF-like material in the placenta prompted us to examine the effect of exogenous LRF on the circulating levels of placental proteins and protein hormones synthesized by the syncytiotrophoblast. Serum levels of chorionic gonadotrophin, pregnancy-specific beta-l-glycoprotein, placental protein five, and placental lactogen remain unaltered for 2 h after an intravenous bolus of LRF (100-300 micrograms) to ten pregnant volunteers admitted for legal abortion between 8 and 18 weeks of gestation. The significance of LRF-like material for the endocrinology of the normal and malignant trophoblast remains to be elucidated.

Luteinizing hormone-releasing factor-like immunoreactivity in islet cells and insulomas of the human pancreas

Luteinizing hormone-releasing factor (LRF)-like immunoreactivity was demonstrated by a three-layer immunoperoxidase method in the islet cells of human pancreas and in the neoplastic cells of insulomas. Adenocarcinomas originating in the exocrine pancreas were LRF-negative. The results demonstrate another hypothalamic peptide-like material in the gastrointestinal tract, the biological role of which remains to be clarified.

Carcinoembryonic antigen in endoscopic brush specimens from benign and malignant gastric lesions

The measurement of carcinoembryonic antigen (CEA) in serum and endoscopic brush specimens was evaluated for the differential diagnosis of malignant and nonmalignant gastric disease. Brush specimens were studied from 33 patients with gastric cancer and 36 patients with benign gastric lesions or apparently normal gastric mucosa. Demonstrable CEA immunoreactivity was found by radioimmunoassay in brush specimens from 24/33 cancer patients (73%) and from 23/36 patients with benign lesions (64%). Patients with CEA+ tissue in the immunoperoxidase test had somewhat higher CEA concentrations in the brush specimens than cases with CEA- biopsy tissue, although overlap was considerable. Thirty-five per cent of cancer patients had both a positive tissue CEA reaction and a CEA/DNA ratio greater than 10 ng/micrograms, whilst patients with benign lesions had only 15% of positives by these criteria (0.01 greater than P greater than 0.001). The serum CEA concentration was above the upper normal level of 5 ng/ml in 2/39 patients, both of whom had gastric cancer. The CEA immunoreactive material from benign and malignant lesions eluted in gel filtration on Sephadex G-200 in the same volume as CEA purified from liver metastases of cancer of the colon, showing that a glycoprotein sharing immunological and physicochemical properties with CEA is present both in malignant and nonmalignant lesions of the gastric mucosa, and that there is considerable overlapping in the amount of CEA. The estimation of CEA in gastric-brush specimens is therefore of limited value in the differential diagnosis of benign and malignant gastric lesions.

Distinction between endocervical and endometrial adenocarcinoma with immunoperoxidase staining of carcinoembryonic antigen in routine histological tissue specimens

The differential diagnosis of endocervical and endometrial adenocarcinomas can be improved by the demonstration of carcinoembryonic antigen (CEA) in tissue by means of immunoperoxidase staining. Tissue from 131 (80%) of 163 patients with endocervical adenocarcinoma but only 11 (8%) of 137 patients with endometrial adenocarcinoma was CEA-positive. The commonest exceptions were endocervical mesonephroid adenocarcinomas (which were CEA-negative) and endometrial adenosquamous carcinomas (which were CEA-positive). After exclusion of these on simple morphological criteria, 86 of 107 endocervical adenocarcinomas (80%) were CEA-positive, and all 122 endometrial adenocarcinomas were CEA-negative. The remarkable difference in the expression of CEA between endocervical and endometrial adenocarcinomas suggests a novel application of immunohistochemistry in routine clinical practice.

Tissue CEA in premalignant epithelial lesions and epidermoid carcinoma of the uterine cervix: prognostic significance

Carcinoembryonic antigen (CEA) was studied by the indirect triple-bridge immunoperoxidase method in formalin-fixed paraffin-embedded tissue specimens from 191 patients with premalignant epithelial lesions or epidermoid carcinoma of the uterine cervix treated 12 years ago. The frequency of tissue CEA positivity was found to increase with advancing clinical disease in the following manner: mild dysplasia, 25%; severe dysplasia, 37%; carcinoma in situ, 60%; invasive carcinoma stage I, 60%; stage IIa, 65%; stage IIb, 80%; and stages III and IV, 69%. The prognostic significance of the tissue CEA positivity was studied in two groups of patients formed on the basis of clinical spread and treatment of the disease. The first group of 60 patients with stage I and IIa cancers had undergone radical surgery. The second group of 44 patients with more advanced carcinoma had been treated by radiotherapy alone. No significant difference in the survival rates was observed in either group between patients with CEA-positive and CEA-negative tumours. In the light of the absence of CEA from normal cervical epithelium, the increasing occurrence of CEA from premalignant lesions to advancing malignant growth suggests that CEA reflects an aggressive potential in premalignant lesions. However, the survival data on patients with CEA-positive and -negative invasive carcinomas suggest that CEA-positive cancers are not more malignant than CEA-negative cancers.

Long-term transplantability and morphological stability of three experimentally induced urinary bladder carcinomas in rats

Three transitional cell carcinomas induced in Fischer 344 rats by a methylcholanthrene pellet or a foreign body inserted locally into the bladder have been serially transplanted in the syngeneic strain for up to 6.5 years. There have been no changes in the individual morphological characteristics of the tumors during this time. Cells cultured in vitro for varying numbers of passages reproduce regularly the morphology of each tumor when they are injected back into the animals and results from a microcytotoxicity assay for cellular immunity indicate that they retain a common, bladder tumor-specific antigen. These tumors are useful for research in turmo biology and are offered to other scientists seeking transplantable carcinomas for experimentation.

Malignant skin tumors of neural crest origin

In a series of 90,000 consecutive surgical biopsies, ten malignant skin tumors were found that revealed at least two of three tissue components known to be derivatives of the neural crest, namely melanotic cells, neuroid structures, and chondrified tissue. The material studied supports a hypothesis presented earlier, that in spite of their morphologic variegation, such tumors from an entity defined by their common origin, the neural crest.