"Catharsis": an excretory function of the epidermis

Cutaneous tuberculosis with a difference: Documenting transfollicular elimination of granulomas

A patient presented with a an asymptomatic brown to erythematous, scaly indurated solitary plaque on his elbow. The lesion was diagnosed as lupus vulgaris on the basis of clinical features and biopsy findings. The histopathology further revealed a granuloma within the follicular infundibulum, which was possibly being expelled out. The phenomenon of transepidermal elimination has been described previously in many conditions, including cutaneous tuberculosis; however, transfollicular elimination of the granuloma has not been reported. We report this unusual phenomenon as a possible mode of elimination of the granuloma.

Human pigmentation: A side effect adapted from a primitive organism's survival, acting through cell attachment with an affinity for the keratinocyte and for elastin: Part I

Pigmentation featured millions of years ago and perhaps began with an amoeba frightening off a predator with some agent such as dopamine to prevent its attachment for phagocytosis by an enemy. This paper suggests that the environmental forces of grip and stick deserve greater emphasis and that mechanical forces involved in grip and stick or release from attachment, all point to control of proteases underlying pigmentation. There is an affinity for elastin as a pathway for melanin to exit its peripheral location in the epidermis into lymphatics and play a humeral role in defense mechanisms. The hair follicle follows the epidermal-dermal pattern of behavior with an affinity for elastin, a controlling function of melanin and through the bulge, an influence of mechanical forces and control by protease inhibitors.

A case of eccrine poroma with multiple transepidermal elimination

The skin functions to eliminate foreign substances through the epidermis to the epidermal surface; this process is called transepidermal elimination (TEE). TEE has been observed in various skin tumors. We encountered a 64-year-old male patient with eccrine poroma with marked TEE. A dark brown nodular papule appeared on the anterior aspect of his right leg about 20 years ago and gradually expanded. Histopathologically, cell nests of poroma were extruded to the epidermal surface at several sites. No erosion was noted, and mild to moderate inflammatory cell infiltration was observed in the upper layer of the dermis. According to Mehregan's classification, the TEE, phenomenon observed in our case may correspond to types 2 and 3.

Perforating dermatoses: a review and report of four cases

Perforating dermatoses, an often overlooked entity comprised of Kyrle's disease, perforating folliculitis, reactive perforating collagenosis, elastosis perforans serpiginosa, and acquired perforating dermatosis, are succinctly described, focusing attention on their clinical features, histopathology, treatment, and pathogenesis. The literature on these facets has been extensively reviewed. In addition, three fresh cases of Kyrle's and one of perforating folliculitis have been incorporated to illustrate these conditions.

Transepidermal elimination of thrombi in three cases of thrombotic angiokeratoma: an incidental histopathologic finding of angiokeratoma

Transepidermal elimination (TEE) is a well known phenomenon by which foreign or altered constituents are removed from the dermis. A thrombosis in the dilated dermal blood vessels of angiokeratoma is not unusual, hence the term thrombotic angiokeratoma. We recently reviewed the histopathologic findings of previously diagnosed cases of angiokeratoma and found that multiple histologic sections of surgical biopsy materials disclosed changes indicating TEE of thrombi in three cases. Special stains searching for an altered substance in those thrombi failed. In this report of three cases, we suggest that this phenomenon could be an incidental and long missed histopathologic finding of angiokeratoma which might explain the fate of these thrombi.

Transepithelial elimination of benign and malignant tumors

Transepithelial elimination is a common physiologic mechanism by which the skin rids itself of externally introduced or endogenously generated waste and foreign material. Although originally observed mostly as a process of elimination of altered connective tissue, transepithelial elimination has recently been described in deep mycoses, bacterial diseases, and nonspecific and foreign-body granulomas. This report describes transepithelial elimination of benign and malignant tumors.

Transepithelial elimination of granulomas in cutaneous tuberculosis and sarcoidosis

Transepithelial elimination of granulomas was observed in histologic specimens taken from involved skin of a patient with disseminated tuberculosis and two patients with sarcoidosis. This phenomenon, previously also observed in other granulomatous disorders, represents one of the skin's several mechanisms to rid itself of endogenous or exogenous waste material.

Transepidermal elimination of actinically damaged connective tissue

Three patients with actinically damaged skin had scaling lesions clinically resembling actinic keratoses. Histologic examination of the lesions disclosed transepidermal elimination (TE) of degenerated (solar elastotic) dermal connective tissue via a transepidermal canal, a previously undescribed phenomenon.

Transepithelial elimination of elastic fibres in the regenerated human epidermis

The elimination of elastic fibres through the regenerated epidermis of human skin was studied using histochemical, immunofluorescent and electron microscopic techniques. No abnormality was detected in the elastic fibres which were being eliminated, but they were in direct contact with the cytomembranes of some lymphocytes and were captured by histiocytes. It seemed that these elastic fibres were recognized as a foreign substance and provoked inflammation. Lymphocytes and histiocytes may play an important role in the transepithelial elimination of elastic fibres.

The perforating disorders

This article reviews the diseases that may show epidermal perforation as a histologic feature. Many of these represent examples of transepithelial elimination (TEE), a mechanism by which the skin rids itself of abnormal substances. After a review of disorders in which perforation is an occasional finding, four diseases that have been considered essential perforating disorders are discussed: elastosis perforans serpiginosa (EPS), reactive perforating collagenosis (RPC), perforating folliculitis (PF), and Kyrle 's disease (KD). A review of the literature, including recent reports of perforating diseases associated with chronic renal failure, suggests that there may be considerable clinical and histologic overlap among PF, KD, and the adult form of "perforating collagenosis." A working classification for the perforating disorders is suggested.

[Dermatoses with transepithelial perforation (author's transl)]

The histologic concept of epidermal elimination of particulate matter was formulated by Pinkus in 1954. Mehregan enlarged on this by recognizing its fundamental role in a variety of skin diseases. The importance of this epidermal reaction pattern in five "perforating" dermatoses is stressed. Also, it is shown that active participation of the corium and epithelio-mesenchymal interaction are required for the iniation of this mechanism. The histological differentiation and histogenesis of the presented dermatoses are discussed.