N S Penneys’s research while affiliated with Washington University in St. Louis and other places

Using an unlabelled antibody peroxidase-antiperoxidase method, we have demonstrated that certain tissue antigens can be identified in tissue sections previously stained with hematoxylin and eosin. This technique is useful in identifying antigens in tissues where insufficient unstained material is available.

A malignant spindle cell tumor with features of a malignant schwannoma presented as a skin mass in the neck of a 13-year-old child. The histologic diagnosis was supported by the demonstration of myelin basic protein within the atypical cells using a monoclonal antibody to myelin basic protein and an unlabelled antibody peroxidase-antiperoxidase technique.

The presence of myelin basic protein (MBP) within a skin neoplasm would support its derivation from Schwann's cells, since this substance is routinely present within Schwann's cells in the peripheral nervous system. Using a monoclonal antibody prepared against MBP and an unlabeled antibody peroxidase-antiperoxidase assay, we surveyed a variety of skin lesions suspected of being derived from Schwann's cells to determine whether MBP was present. Myelin basic protein was detected within the cytoplasm of cells composing benign solitary schwannoma (neurilemmoma) and neurofibroma, confirming the association of these lesions with proliferation of Schwann's cells. Myelin basic protein was not found in a variety of intradermal and compound nevus cell nevi nor in malignant melanoma. This negative finding supports electron microscopic evidence suggesting that nevus cells have no relationship to Schwann's cells even though some nevus cell arrangements suggest Schwann's cell derivation under the light microscope.

Dermatologists and dermatopathologists have become familiar with immunohistochemical techniques through the routine use of immunofluorescence, both direct and indirect methods, to confirm the diagnosis of such diseases as pemphigus, dermatitis herpetiformis and lupus erythematosus. During the past decade, sensitive immunohistochemical techniques have been developed for the demonstration of antigens in tissue sections. These techniques involve the use of both unlabelled and enzyme-labelled antibodies; the most popular of these uses horse radish peroxidase as the enzyme label and is called the immunoperoxidase technique. The principle of this technique is discussed.

• Pancreatitis developed in a 12-year-old girl with a one-year history of systemic lupus erythematosus. The pancreatitis was first manifested by panniculitis of the lower extremities. Calcinosis cutis subsequently developed, both in areas of panniculitis and in areas free of panniculitis. The patient's medications at the time of onset of pancreatitis included prednisone, hydrochlorothiazide, and azathioprine, all of which have been reported to be causes of pancreatitis. We wish to alert physicians that pancreatitis associated with cutaneous panniculitis and calcinosis cutis may develop in children with systemic lupus erythematosus. (Arch Dermatol 1983;119:491-494)

A variety of benign and malignant skin lesions was stained for the presence of prekeratin using an unlabeled antibody peroxidase-antiperoxidase method and an antibody raised against human prekeratin protein. No prekeratin could be detected in benign or malignant lesions derived from melanocytes, and prekeratin could not be found in atypical fibroxanthoma, Kaposi's sarcoma, angiosarcoma, dermatofibrosarcoma protruberans, and leiomyosarcoma. Paget's cells did not contain prekeratin. Varying staining intensities were observed in keratinocytic atypical hyperplasias. Of particular interest is the observation that many spindle cell lesions that were difficult to identify with 100% assurance from routine stains could be positively identified as squamous cell carcinoma after prekeratin was found in the atypical cells.

Myelin basic protein, a substance found in neural structures, has been demonstrated in cutaneous granular cell tumors using a monoclonal antibody generated against myelin basic protein and an immunoperoxidase method. The substance was not found in fibrohistiocytic skin lesions. The presence of myelin basic protein in granular cell lesions of the skin supports the concept that this lesion is related closely to nerve structures.

An immunoperoxidase technique was used to test for cytomegalovirus (CMV) proteins in lesions of Kaposi's sarcoma from 19 patients with acquired immune deficiency syndrome (AIDS) and 3 patients without AIDS. CMV proteins could not be detected in any of the cases of Kaposi's sarcoma. Thus, while CMV genetic material may be present in these cells, the virus is not actively directing the synthesis of proteins. This eliminates reactivation of latent CMV in tumor tissue, or late infection of Kaposi's sarcoma cells as explanations for the elevated antibody titers to CMV and other evidence of CMV infection in patients with Kaposi's sarcoma. However, the possibility remains that exposure to CMV occurs as a primary event in the development of Kaposi's sarcoma. These findings indicate that, as in Kaposi's sarcoma of the elderly, the virus is inactive in Kaposi's sarcoma cells of patients with AIDS, and there is no difference between the two lesions in immunoperoxidase staining for CMV proteins.

Carcinoembryonic antigen was demonstrated in sweat gland adenomas by immunostaining using standard immunoperoxidase techniques. Carcinoembryonic antigen could not be found in adnexal tumors derived from the pilar and sebaceous apparatus. The demonstration of this specific antigen in certain sweat gland tumors may be helpful in the recognition and classification of these kinds of lesions.