Sandbox:Zoon balanitis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]Associate Editor(s)-in-Chief: Vishal Devarkonda, M.B.B.S[2]

Synonyms and keywords:Balanoposthite chronique circonscrite bénigne á plasmocytes, Balanitis chronica circumscripta plasmacellularis

Overview

Zoon's balanitis is an idiopathic, chronic, benign inflammatory mucositis of the genitalia. 

Historical Perspective

• In 1952, for the first time in medical literature, Zoon recognized a distinct entity in patients with chronic balanitis, named it as balanoposthite chronique circonscrite bénigne á plasmocytes” or “balanitis chronica circumscripta plasmacellularis.
• In 1954, Garnier reported the similar lesion in vulva.
• In 1956, Nikolowski described the identical lesion in oral mucosa.
• In 1963, Kortnig described the idential lesion in conjuntiva.

Classification

There is no established classification system for Zoon balanitis.

Pathophysiology

Pathogenesis

Etiology and pathogenesis of this condition are still speculative. As it is mostly seen in uncircumcised men, it is thought to be because of irritation, due to retention of urine and smegma in context of “dysfunctional prepuce,” leading to poor genital hygiene and repeated local infection.[9] In addition, trauma, friction, heat, and constant rubbing may be a contributory factors.[9] Thus, the two most important triggering factors are the constant exposure of the mucosa to humid condition and to chronic irritation.[10] This explains why lesions of ZB undergo prolonged remission after circumcision.[10]

In addition, other possible causes of ZB that have been described in the literature include chronic infection with Mycobacterium smegmatis and human papillomaviruses (HPV).[11] However, no evidence has yet been reported for bacterial infection and polymerase chain reaction has also failed to detect DNA of HPV.[12] Similarly, there is no evidence for the supposition that ZB may be caused by local disturbance of circulation.[13] It has also been related to lichen aureus due to marked hemorrhage in association with lichenoid infiltrate that is seen in ZB.[14] However, lichen aureus usually affects the lower limbs and is not associated with common histopathological signs of ZB such as erosions, neutrophils, and plasma cells. Thus, there is a lack of supportive evidence for this hypothesis.[13] Furthermore, there is no supportive evidence for the hypothesis given by Nishimura et al.,[15] who had suggested that immediate hypersensitivity response mediated by IgE class of antibodies plays an important role in the etiopathogenesis of ZB. Hyman and Leider speculated that “extramedullary plasmacytic infiltrations that persists are expressions of occult multiple myeloma” and could be a cause ZB.[16] However, it has been contradicted by subsequent studies that have demonstrated clearly the polyclonal nature of the plasmacytic infiltration in ZB.[13]

Histopathology

ZB has very distinct histopathological changes affecting both epidermis and dermis.[13]

Epidermal changes → Earliest histopathological changes show epidermal thickening, acanthosis, and parakeratosis. This is followed by epidermal atrophy, at times erosions and spongiosis. These superficial erosions can be associated with scattered neutrophils in the upper reaches of epidermis. Accentuation of spongiosis occurs in the lower half of the spinous zone. Additional features such as subepidermal clefts, necrotic keratinocytes, and lozenge keratinocytes (i.e., elongated keratinocytes in the lower half of the spinous zone arranged parallel to the skin surface) may be seen in the later stages of ZB.

Dermal changes → Initially, there is a patchy lichenoid infiltrate of lymphocytes and some plasma cells in papillary dermis, which is subsequently replaced by dense band-like infiltrate of plasma cells, neutrophils, eosinophils, lymphocytes, and erythrocytes. Among all these infiltrate, plasmocytes are predominant usually exceeding 50% of all the cells. It may be associated with siderophages (i.e., macrophage that has absorbed iron-containing particles), hemosiderin deposition and extravasated red blood cells. Changes in dermal vasculature include vascular dilatation with singular vertical or oblique orientation of proliferated individual vessels, which is characteristic of ZB. These are more common in cases with a dense infiltrate. In the later stages, upper dermis shows fibrosis which correlates well with subepidermal clefts, epidermal atrophy, and plasma cell infiltrates. Immunohistochemical studies of plasmocytes in ZB show that plasmocytes produce immunoglobulin G (IgG) predominantly to a lesser degree IgA and IgM.[10]

It is relatively simple to differentiate the premalignant lesions from ZB histopathologically as one can see dysplastic epithelium in the premalignant lesions while it is absent in case of ZB. Histologically, benign conditions such as pemphigus vulgaris, flexural psoriasis, lichen planus, and Reiter's disease may show features in common with ZB but lack the typical changes in the epidermis and dermal blood vessels.

Screening

There is no established screening guidelines for Zoon balanitis