Diagnostic and prognostic tests l. If direct immunofluorescence (IF) points to pemphigus, confirm with indirect IF and ELISA serum studies for pemphigus antibodies* and, if indicated, with light microscopy. 2. If serum studies confirm biopsy findings of pemphigus and lesions persist, check treatment responses with repeat indirect IF tests, at first at about monthly intervals, until lesions subside. 3. Check all positive serum findings for pemphigus with biopsy studies. In problem cases, do special serum and/or biopsy studies as needed

CONFIRMATION OF DIAGNOSIS OF PEMPHIGUS - Since pemphigus may be fatal, all cases should be confirmed by both biopsies and serum studies (1, 2, UPDATE*). Particularly in cases with mucosal lesions, light microscopic studies should be included.

PROGNOSTIC STUDIES IN PEMPHIGUS - Changes in titers of antibodies that cause pemphigus aid in evaluating responses to treatment. Thus, indirect immunofluorescent (IF) titer changes afford a useful guide in the therapeutic management of patients. Titers of peMphigus antibodies rise at or before a relapse and fall as patients respond to therapy. If therapy is stopped while these antibodies are still present or reappear, patients usually have relapses. (See figure).

Serum tests should be performed preferably every 2 to 4 weeks until the disease is in remission. During remission, the tests may be repeated every 1 to 6 months. (1)

Since tests for changes in antibody titers require comparisons of old and new sera, Beutner Laboratories (BL) saves sera of all pemphigus cases for parallel testing with future sera using indirect IF tests with monkey esophagus particularly for pemphigus vulgaris and with guinea pig esophagus for pemphigus foliaceus (3). The ELISA method for desmoglein 1 and 3 (Dsg1 and Dsg3) developed by Amagai et al., (4-6), which can give similar results, aids in ruling out biologic false positives in problem cases.

* See "Pemphigus: Immunopathologic diagnosis with biopsies and serum studies".

SPECIAL PROBLEMS

Differentiation of the vulgaris and foliaceus forms of pemphigus - While the presence of mucosal lesions differentiates pemphigus vulgaris and its variants (pemphigus vegitans, paraneoplastic pemphigus) from pemphigus foliaceus and its variants (pemphigus erythematosus and most cases of IgA pemphigus and pemphigus herpetiformis), and while these two basic forms of pemphigus can be distinguished by light microscopy in most (but not all) cases, serum studies for Dsgl and Dsg3 ELISA methods can aid in differentiating them in problem cases. Amagai et al. (4,5) observed that 97.9% of 48 pemphigus foliaceus cases examined by ELISA methods had at least borderline index values of Dsgl and little or no Dsg3 reactions.

Confirmatory tests for pathogenic pemphigus antibodies - Active cases of pemphigus typically have antibodies of the IgG4 subclass. But first degree relative of pemphigus cases and cases with low disease activity with antibodies to desmoglein 1 and 3 and antibodies by the IIF tests have antibodies of IgG1 and IgG2 subclasses with little IgG4 antibody activity (7). Thus, tests for IgG4 pemphigus antibodies aid in identifying active cases. Specifically, three tests serve to differentiate pemphigus-like and blood group antibodies from true pemphigus antibodies: a) Dsgl and/or Dsg3 ELISA methods are positive, b) IgG4 IIF tests are positive in pemphigus and c) complement fixing IIF tests which are negative in pemphigus.

Paraneoplastic pemphigus - As defined by the group of Anhalt (8-11), this condition includes cases with pemphigus vulgaris, pemphigoid or coexistence of both together with a systemic malignancy. The condition is characterized by multiple antibodies that coexist with true pemphigus antibodies as seen by IIF and Dsg3 and Dsgl ELISA. Antibodies to the transitional epithelium of rat bladder appear in most cases (8); IIF tests for these antibodies have a reported specificity of 83% and a sensitivity of 75% complement fixing IF tests increases the latter to 89% (10). Most patients have extensive oral and skin lesions and die within a year.

REFERENCES
1. Jablonska S, Chorzelski , Beutner EH, Michel B, Cormane RH, Holubar K, Bean SF, Blaszczyk M, Ploem J, Saikia NK Uses for IF tests of skin and sera: Utilization of immunofluorescence in the diagnosis of bullous diseases, lupus erythematosus and certain other dermatoses. Arch Dermatol 111:371-381,1975.
2. Beutner EH, Chorzelski TP, Jablonska S Ed. Clinical significance of immunofluorescence tests of sera and skin in bullous diseases: A cooperative study. In "Immunopathology of the Skin", 3rd edition. Ed, EH Beutner, TP Chorzelski, V Kumar, Eds, John Wiley and Sons, New York, 177-205, 1987.
3. Sabolinski ML, Beutner EH, Krasny S et al. Substrate Specificity of Anti-Epithelial Antibodies of Pemphigus Vulgaris and Pemphigus Foliaceus Sera in Immunofluorescence Tests on Monkey and Guinea Pig Esophagus Sections. J Invest Dermatol 88: 545-549, 1987.
4. Stanley JR. Cell adhesion molecules as targets of autoantibodies in pemphigus and pemphigoid, bullous diseases due to defective epidermal adhesion. Advances in Immunol 53: 291-325, 1993.
5. Amagai M, Tsunoda K, Zillikens D, et al. Clinical phenotype is defined by the antidesmoglein autoantibody profile. J Am Acad Dermatol 40:167-70,1999.
6. Amagai M, Komai A, Hashimoto T, Shirakata Y, Hashimoto K, Yamada T. Usefulness of enzyme-linked immunosorbent assay using recombinant desmoglein 1 and 3 for se.rodiagnosis of pemphigus. Brit J Dermatol 140:351-57,1999.
7. Kritcheli D, Davis M., Frusic-Zoltkin M, Michel B, Milner Y. The distribution of pemphigus vulgaris-IgG subclasses and their reactivity to desmoglein 1 & 3 in pemphigus patients and their first degree relatives. J Invest Dermatol 112: 612, 1999 (Abstr.#550). 8. Nousare HC, Kimyai-Asadi, Anhalt GJ. Clinical and immunologic features of Paraneoplastic pemphigus. J Invest Dermatol 112: 567, 1999 (Abstr.#270).
9. Fried R, Lynchfield Y, Anhalt G et al. Paraneoplastic pemphigus appearing as bullous pemphigoid-like eruption after palliative radiation therapy. J Am Acd Dermatol 29: 815817, 1993.
10. Helou J, Allbritton J, Anhalt GJ. Accuracy of indirect immunofluorescence testing in the diagnosis of paraneoplastic pemphigus. J Am Acd Dermatol 32, 441-447,1995.
11. Chorzelski TP, Hashimoto T, Maciejewska, Amagai M, Anhalt GJ. Paraneoplastic pemphigus associated with Castleman tumor, myasthenia gravis and brochiolitis obliterans. J Am Acd Dermatol 41:393-400,1999.

Copyright © 2001 Beutner Labs, Inc.
Published with permission.