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Continuous dermoepidermal junction IgM detected by direct immunofluorescence: A report of nine cases Thomas N. Helm, MD, a and Rafael Valenzuela, MD, PhD b Cleveland, Ohio

Background: Although a linear IgM dermatosis of pregnancy has been reported, other authors have not found evidence for a distinct linear IgM dermatosis. Objective: We set out to determine whether or not continuous dermoepidermaljunction IgM deposition detected by direct immunofluorescence was indicative of a specific disease. Methods: We collected nine cases during a 9-year period in which biopsy specimens for direct immunofluorescence revealed continuous linear IgM at the dermoepidermaljunction in the absence of other immunoglobulins. In all of these eases the medical record was available for review. Results: Clinical correlation revealed that these patients had a heterogeneous group of diseases with urticaria and leukocytoclastic vasculitis being most common. No diagnostic specificity could be ascribed to the linear IgM pattern, although six of our nine cases could be considered manifestations of a hypersensitivity response (e.g., urticaria, leukocytoclastic vasculitis, pigmented purpuric dermatosis, or hypersensitivity dermatitis). Conclusion: Pathologists and dermatologists should be aware that linear IgM can be seen in a variety of clinical settings. The etiopathogenic significance of this finding, if any, remains to be determined. At present, the finding must be viewed as nonspecific. (J AM ACAD DERMATOL1992;26:203-6.) IgM is the first immunoglobulin produced after an antigenic challenge, and IgM is frequently deposited along with other immunoglobulins in a variety of autoimmune blistering diseases. A diffuse granular pattern of IgM along the dermoepidermal junction is a possible manifestation of a positive lupus band test, 1 but focal IgM may or may not be a specific finding. A diffuse linear pattern of IgM has only rarely been reported,2, 3 and in only one case did this finding seem to have clear clinical significance. We evaluated cases with diffuse dermoepidermal linear IgM in the absence of other irnmunoglobulins to see whether any clinical patterns emerged. METHODS From November 1982 to February 1991, approximately 2750 skin biopsy specimen were evaluated by direct immunoftuorescence in our laboratory. Direct iraFrom the Departments of Dermatologya and ImmunopathoIogy,b The Cleveland Clinic Foundation. Accepted for publication Aug. 30, 1991. Reprint requests: Rafael Valenzuela, MD, Department of Dermatology, The Cleveland Clinic Foundation, One Clinic Center Dr., Cleveland, OH 44195-5031.

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munofluorescence was performed as previously described.4 Immunofluorescent patterns were interpreted according to standard criteria: RESULTS A diffuse linear deposition of IgM along the dermoepidermal junction of the basement membrane zone without the presence of other immunoglobulins was noted in l0 cases or approximately 0.4% (Fig. 1). Medical records were available for review in nine of these cases. Retrospective review of the medical records revealed that the ages of our patients ranged from 34 to 74 years. Five were women and four were men. The duration of their eruption varied from 8 days to 2 years. The morphology of skin lesions ranged from palpable purpura to papular erythema or urticaria. One patient had only mucositis and urethritis. The final diagnoses in these cases were as follows: urticaria (two patients), leukocytoclastic vasculitis (two), pigmented purpuric dermatosis (one), hypersensitivity dermatitis (one), folliculitis (one), paraneoplastic pemphigus (one), and Grover's disease (one) (Table I). In only three of our nine cases was the biopsy material from normal skin. 203

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Journal of the American Academy of Dermatology

H e l m and V a l e n z u e l a

T a b l e I. Clinical data of nine patients with IgM deposition along basement membrane zone Cases

I

2

3

J

Age (yr) Sex Morphology

54 M Palpable purpura

39 F Papules and excoriations

36 F Nonspecific papular erythema

79 M Excoriated papules on back and neck

Duration DIF

1 mo Diffuse linear IgM 2+ D-E and vascular fibrinogen

6 mo Diffuse linear IgM (1+)

8 days Diffuse linear IgM (1+)

2 yr Linear IgM 2+ K (1+) and X (1+)

Location for D[F Laboratory findings

-Cryos 608 K & X IgM & IgG

Normal skin ANA RF neg

Lesional skin Microcytic anemia, LDH Coombs neg

Final Dx

Leukocytoclastic vasculitis from cryoglobulinemia

Hypersensitivity dermatitis

Histologic Dx (H &E)

Leukocytoclastic vasculitis

Hypersensitivity dermatitis

Normal skin ANA >1:640, gamma globulins increased Leukocytoclastic vasculitis and connective tissue disease Erythema group reaction

Location

--

Legs and arms

Legs (below knees)

Folliculitis with excoriations Rt side of back, suppurative folliculitis

Back, abdomen, arms, hands

ANA, Antinuclearantibody;CLL, chroniclymphocyticleukemia;D-E, dermoepidermaljunction;eos,eosinophils;LDH, lactatedehydrogenase;PemBMZ, pemphigoidbasementmembranezone antibodies;Pem-ICS, pemphigusintercellularsubstanceantibodies;RF, rheumatoidfactor.

*This case will be part of a detailedpublicationby Camisa et al. on paraneoplastic~mphigus in an upcomingissueof this JOU~N^L.

Fig. 1. Case 7. Diffuse linear IgM (2+) at dermoepidermal junction. (?