Primary Epithelial Germ Research Articles

An unusual hematopoietic proliferation seen in a nevus sebaceous

Nevus sebaceous is a tumor of primary epithelial germ cells that is generally first noticed at birth. It is relatively quiescent until puberty when a variety of benign and potentially malignant tumors may arise within it. We describe a nevus sebaceous with immature fat cells, vascular ectasia, and extramedullary hematopoiesis that was present at birth. At 4 months, the immature adipose and hematopoietic elements, as well as the vascular changes, had resolved. (J Am Acad Dermatol 2000;42:881-2.)

Mixed tumors with follicular differentiation: complex neoplasms of the primary epithelial germ.

Some mixed tumors of the apocrine variety also show characteristics of follicular and/or sebaceous differentiation. This can be explained because of the common embryologic origin of the three structures in the primary epithelial germ of the superficial ectoderm. Twenty specimens of apocrine mixed tumors were studied by conventional microscopy. The specimens were evaluated searching for some features of folliculo-sebaceous differentiation. Certain features of folliculo-sebaceous differentiation were found in 45% of the samples examined. Additionally, different tumoral architectures were observed, resembling several well-characterized adnexal organoid neoplasms. In some tumors, there were also follicular structures of mesenchymal origin, similar to the dermal hair papilla and the arrector pili muscle. Apocrine mixed tumors of the skin illustrate the ability of pluripotential primordial cells to differentiate in different directions within an individual tumor. Moreover, mixed tumors appear as a compendium of different folliculo-sebaceous neoplasms. We suggest that these proliferations should be interpreted as "complex neoplasms of the primary epithelial germ."

Ultrastructural resemblance of basal cell epithelioma to primary epithelial germ.

Six examples of basal cell epithelium were compared to fetal and adult skin. Five parameters were used in this study: abnormally large aggregates of melanosomes in epithelial cells; the paucity of half-desmosomes; the increase of microfilaments in the cell periphery; clustered membrane-limited granules; and desmosome-like structures of stromal fibroblasts. All of these indicators were positive in both basal cell epithelioma and fetal hair follicle; but they were negative in both fetal and adult epidermis. Therefore, it was concluded that basal cell epithelioma seems to mimic fetal primary epithelial germ. Interestingly, stromal fibroblasts of basal cell epithelioma phagocytize collagen fibers, and membrane-limited granules were found both inside and outside the tumor cells facing the digested collagen stroma. In view of the collagenolytic activity of the homogenate of basal cell epithelioma, membrane-limited granules might represent zymogen granules for collagenases.

Trichoepitheliom mit Strukturen eines apokrinen Adenoms

A tumor showing features of both trichoepithelioma and apocrine adenoma is reported. The combined manifestation of these two neoplasms may be explained by their common origin from the primary epithelial germ or the pkiripotentiality of the epidermal cells.

Linear Unilateral Basal Cell Nevus With Comedones

A patient is presented and the literature of previously reported cases is reviewed, of a rare nevoid disorder which involves the skin and possibly the axial skeleton. The cutaneous lesion consists of a unilateral and extensive eruption, usually present since birth, and consisting of numerous basal cell epitheliomas, comedones and cysts, and areas of atrophy. The clinical and microscopic findings are presented and this lesion is clearly distinguished from the basal cell nevus syndrome. The relationship of the lesions to the primary epithelial germ is also considered.

Calcifying Epithelioma of Malherbe: Histochemical and Electron Microscopic Studies

Calcifying epithelioma is a rare, solitary tumor which often occurs in young individuals (1), most frequently on the face and the arms (1, 2). Since Malherbe and Chenantais (3) described “calcified epithelioma of sebaceous glands” in 1880, the histogenesis of this tumor has been attributed to various skin appendages such as sebaceous glands (3, 4) and hair (2, 5, 6, 7). Lever and Griesemer (7) regarded the basophilic cells in calcifying epithelioma as primary epithelial germ cells with a tendency to differentiate into keratotic hair cells. Forbis and Helwig (1), in their recent study on 240 specimens, agreed with the opinion of Lever (2) and Lever and Griesemer (7) that calcifying epithelioma arises from primitive cells of the hair matrix. They pointed out that the broad dense transitional zone from basophilic to shadow cells of this tumor, where sulfhydryl groups are abundant, is analogous to the kera-togenous zone of the hair. They also demonstrated that hyalinized shadow cells in some instances show a brilliant birefringence, as does the keratogenous zone of the hair.

BASAL CELL EPITHELIOMA OF THE SOLE.

In reporting the sixth case of basal cell epithelioma of the sole, it is suggested that basal cell epitheliomas derive from `pluripotential epithelial cells which may differentiate into any of the epithelial structures of the skin. The current consensus that basal cell epitheliomas derive from cells analagous only to primary epithelial germ cells is considered to be too restrictive.

POSSIBLE ANALOGOUS CUTANEOUS AND ODONTOGENIC TUMORS.

Basal cell epithelioma, ameloblastoma, premalignant fibroepithelioma, ameloblastic fibroma, cutaneous calcifying epithelioma, and calcifying odontogenic cyst were compared microscopically. Due to their common origins in primary epithelial germ cells, it is not surprising that many similarities in microscopic morphology exist.

ECCRINE POROMA. REPORT OF THREE CASES, TWO WITH AN UNUSUAL LOCATION.

Eccrine poroma is a benign tumor composed of poral epithelium. The usual location is on the volar surfaces of the hands or feet, and the usual time of onset is after the age of 40. Three new cases are presented. Two of these had unusual localization and gross configuration. One case was unusual with respect to an early age of onset. It is proposed that eccrine poroma arises from pluripotential cells with a tendency to form poral epithelium and that its histogenesis is analogous to the primary epithelial germ tumors.

PILOMATRIXOMA (CALCIFYING EPITHELIOMA) IN CHILDREN

A clinicopathologic analysis of 92 pilomatrixomas in 84 children was made. The diagnosis is seldom made clinically, since the lesions are not distinct and are referred to most often as some variety of cyst. The common locations are the face, neck, and arms. The lesion is benign and is cured by excision. In our patients the diagnosis was always established by pathologic study. There are similarities between pilomatrixoma and pilar structures. The tumor probably originates from a primitive cell of the primary epithelial germ and differentiates toward hair-matrix cells. The name "pilomatrixoma" is acceptable, since it conveys the histogenesis of the lesion and avoids the word "epithelioma," which generally indicates a malignant neoplasm and should not be used for this benign tumor.

Basal-Cell Epithelioma on Nevus

This is the report of a rare1disease, nevus syringocystadenomatosus papilliferus (Werther), complicated by a superimposed superficial type of basal-cell epithelioma. It is Lever's2belief that basal-cell epitheliomas occur only in areas where primary epithelial germ structures (hair, sebaceous or apocrine glands) are found. They may be present in the same lesion with nevus sebaceous, syringocystadenoma papilliferus, sebaceous epithelioma, or trichoepithelioma. It is also his thought that basal-cell epitheliomas are not carcinomas, not derived from basal cells, but are nevoid tumors (hamartomas) originating from arrested embryonal primary epithelial germ cells. The proposition, concerning the nonmalignant nature of this tumor, is based on the fact that they probably never metastasize as such, and the reported metastesizing basal-cell epitheliomas, although rare, could represent a wrong diagnosis.3 Tumors showing an intermediate stage of differentiation between basal-cell epithelioma and any one of the benign epitheliomas as mentioned do occur and have been reported.2

A mixed tumor occurring as a syringocystadenoma papilliferum with a nevus sebaceus; report of a case.

When an uncommon histologic specimen is encountered, it stimulates interest, but when two rather uncommon conditions appear as a single clinical finding, they call for an even greater degree of study and speculation. It is for these reasons and for the purpose of adding another case to the records 1,2 that a case of syringocystadenoma papilliferum associated with a nevus sebaceus is submitted for publication. Furthermore, the finding of these two histologically different lesions as a single mixed tumor gives support to the belief that they have a common embryologic origin, the primary epithelial germ. 3 Much evidence is already documented showing that the nevus syringocystadenoma papilliferum is a tumor of the apocrine ducts, having developed as a hamartoma through dysembryogenesis. The nevus sebaceus also has as its anlage an epidermal appendage, namely, the sebaceous gland. Since the anlage for the sebaceous and apocrine glands, as

Calcifying epithelioma of malherbe in the dog: A pseudoparotid tumor

B of its relative rarity in the human being and its heretofore unreported occurrence in the dog, and because this lesion may entail a diagnostic pitfall, we felt that this report might be of more than routine interest. Calcifying epithelioma in man is manifest usually in the second or third decade as a hard, solitary, rounded tumor situated deep in the subcutaneous tissues. It is covered by normal uninvolved skin and is freely movable with it. It may attain considerable size; tumors 5 cm. in diameter have been observed. It is usually found in the upper extremities, face, neck, or back, well demarcated from the surrounding structures of the deep corium or subcutaneous fat by a well-developed capsule of collagenic connective tissue. The histologic appearance is quite characteristic for this tumor. Irregularshaped masses of epithelial cells are separated from one another by thin strands of fibrous connective tissue. The epithelial cells are of two kinds, a germinative or basal-cell type and a “shadow cell” that occurs in sheets. There is marked similarity in the appearance of the basal cells and those of basal-cell cpithelioma, and this erroneous diagnosis may be made if sufficient care is not exercised. The basophilic cells are rounded or elliptical and composed of nearly all nucleus, the cytoplasm being quite scant.? The “shadow cells” are pale eosinophilic masses of epithelial cells that have lost their nuclear hematoxylinophilic property but not their individuality. One can often see areas of transition between the two cell forms. Sheets of cornified cells can be found either in the basophilic cellular masses or in the “ shadow cells. ” These keratinized nests arc prone to undergo calcification. The stroma quite frequently manifests a number of foreign body giant cells either near the pale cosinophilia “shadow cells” or near an area of hemorrhage, both of which were observed in the case to be described. Occasionally bone may be found in the connective tissue strands or in areas where calcification has previously occurred. There are many theories of histogenesis : calcification of a sebaceous gland epithelioma,l misplaced cpithelial rests of sebaceous glands,= degenerating basal-cell carcinoma,3 hair matrix cells,4’ 5 and primary epithelial germ cells.G

PATHOGENESIS OF BENIGN TUMORS OF CUTANEOUS APPENDAGES AND OF BASAL CELL EPITHELIOMA

THE PATHOGENESIS of basal cell epithelioma has so far not been satisfactorily determined. In this communication, an attempt is made to show that basal cell epitheliomas are not carcinomas but related to the so-called benign epitheliomas, cutaneous adenomas and nevi organomatosi. Evidence will be presented that the tumors belonging to these four groups are nevoid tumors, or hamartomas, originating, in accordance with the Cohnheim theory, from arrested embryonal cells, in this instance from cells of the primary epithelial germ. Variations in the degree and in the direction of differentiation prior to the onset of neoplasia would explain adequately the wide variety of histologic pictures presented. A classification of the tumors originating from the primary epithelial germ will be presented, following which the various types of tumors included in this classification will be discussed. DEVELOPMENT OF THE EPIDERMIS Since my intention is to show that the tumors which are the subject

PATHOGENESIS OF BENIGN TUMORS OF CUTANEOUS APPENDAGES AND OF BASAL CELL EPITHELIOMA

IT IS THE thesis of this paper that the basal cell epitheliomas originate from incompletely differentiated embryonal cells rather than from dedifferentiated anaplastic cells. It is my belief that basal cell epitheliomas are not carcinomas, not derived from basal cells, but are nevoid tumors (hamartomas) derived from arrested embryonal primary epithelial germ cells. They represent the least differentiated group of primary epithelial germ tumors. In my classification of the primary epithelial germ tumors they are grouped as nonorganic hamartomas (table in part I). 1 The name basal cell epithelioma has been retained in spite of my belief that basal cell epitheliomas do not originate from basal cells, because its use is so well established. The designation basal cell carcinoma should, however, be avoided. The proposition that basal cell epitheliomas are not carcinomas is based on the fact that they probably never metastasize. Niles 2 stated that metastasis of a pure