IgG4-related Skin Lesion with Mikulicz's Disease.

Sir,

IgG4-related disease shows common pathologic features of increased serum IgG4 level and IgG4-positive plasma cell infiltration associated with fibrosis.[123] Various organs are involved including lacrimal glands, salivary glands, lung, liver, kidney, pancreas, retroperitoneum, breast, pituitary gland, and prostate. Mikulicz's disease is among the IgG4-related diseases, and is characterized by sclerosis/fibrosis, lymphocytic infiltration and atrophy of the lacrimal glands and salivary glands.[4]

A 32-year-old female was admitted to our hospital with pruritic erythematous papular skin eruption on the face and trunk of 3 weeks duration. Clinical examination showed the patient also had protrusion of bilateral eyes, and submandibular swelling of 12 months duration before the occurrence of the skin eruption [Figure 1a and b]. She had no history of allergies. Blood eosinophil count was 875/μl accounting for 10.2% of the total blood cell count. Serum IgG level was 1430 mg/dl with IgG4 426 mg/dl (29.8%). Computed tomography (CT) scans revealed swelling of bilateral lacrimal gland and parotid glands without lymphadenopathy. No abnormal finding was detected in lung, liver, or pancreas. Skin biopsy of the facial papular lesion revealed lymphocytic infiltration of vessels and adnexal structures in the dermis [Figure 1c]. Biopsy of salivary glands showed marked lymphocyte and plasma cell infiltration accompanied by eosinophils [Figure 1d]. Immunohistochemical study revealed numerous IgG4-positive cells. The average IgG4 positive cells in skin and salivary glands were 65% and 71% in 5 randomly-selected high-power fields, respectively [Figure 1e and f]. The patient was diagnosed as Mikulicz's disease showing features of IgG4-related disease. Systemic administration of 30 mg prednisolone resulted in rapid improvement of skin lesions. The swelling of lacrimal glands and parotid glands subsided and serum IgG4 levels returned to normal range. No recurrence of the abnormal findings was detected by 10 mg systemic prednisolone treatment.

Figure 1

Clinical feature and histopatological examination of the patients (a) Swelling of bilateral upper eyelids. (b) Erythematous papular skin lesions on the right cheek. H.E histopathological examination of skin lesion (c) salivary gland (d) fibrosis and infiltration of lymphocytes and plasma cells. Immunohistochemical examination of skin lesion (e) salivary gland (f) infiltration of IgG4 positive plasma cells

IgG4 does not activate complement via the classical pathway because of its low affinity for C1q and Fc receptors, suggesting a low potential for immune activation. Thus, IgG4 is supposed to prevent large immune complex formation and shows inhibitory effect against allergic reactions. In the presence of abnormal expression of IgG4, however, various abonormalities are induced in the lacrimal glands, salivary glands, lung, liver, kidney, and in the skin.

Mikulicz's disease was previously assumed to be a subtype of Sjogren syndrome. However, because of increased serum levels of IgG4 and infiltration of IgG4-expressing cells in the lacrimal and salivary glands, Mikulicz's disease is now included in IgG-4 related disorders.[5] Only a few reports exist describing skin lesions associated with IgG4-related disease.[6] Mikulicz's disease accompanied with reactive perforating collagenosis,[7] and erythematous nodules[6] have been described. In this report, we described Mikulicz's disease with erythematous papular lesion on the face and trunk with IgG4-positive cells in the dermis. Because no definite criteria for the diagnosis of recently identified IgG4-related disease exist, only small number of cases has been described in the literature. Thus, we suppose that IgG4-related disease with erythematous papular skin eruption is more prevalent, which should be recognized in the dermatological field.

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