Description

A 54-year-old man with thymoma (figure 1A, arrow) diagnosed 8 months previously was referred to our hospital because of a 5-month history of painful oral ulcer and odynophagia. Physical examination showed erosion of the lips, pharynx, tongue and buccal mucosa (figure 1B, arrow), together with scrotal skin change (appearing similar to lichen planus; figure 1C, arrow heads) and scrotal erosion (figure 1C, arrow). On H&E staining, scrotum-biopsied specimens showed suprabasilar blisters with acantholysis (figure 1D, asterisk). On direct immunofluorescence, intercellular IgG and C3 deposits were noted, but not at the basement membrane. Indirect immunofluorescence studies of dilutions of the patient’s serum applied to a human skin substrate revealed circulating antibodies that bound to the intercellular regions (not to basement-membrane zones) of the epithelium at a titre of 1–160, whereas that applied to a rodent bladder substrate (negative control slides) did not. All serum antibodies to desmoplakin I and II, envoplakin and periplakin and desmoglein 1, were negative, but only serum desmoglein 3 antibody was positive on CLEIA (chemiluminescence enzyme immunoassay) (1:840) or ELISA (269.85).

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Figure 1

Enhanced thoracic MRI showed the presence of a homogenously enhanced 3 cm mass. Mucous membrane erosion of the lips, pharynx, tongue and buccal mucosa (B, arrow) were noted together with scrotal skin change (C, arrow heads) and scrotal erosion (C, arrow). On H&E staining, scrotum-biopsied specimens showed suprabasilar blisters with acantholysis (D, asterisk).

Therefore, the patient was diagnosed as not paraneoplastic pemphigus (PNP) but pemphigus vulgaris (PV). In PV, antibodies to desmosomal proteins are associated with the detachment of keratinocytes from one another (ie, acantholysis), producing a suprabasal cleft, as in the present case. Whereas in PNP, antibodies to desmosomal and hemidesmosomal proteins are associated with both suprabasal and subepithelial clefting.

PNP and PV have similar clinical presentations but have different pathophysiologies1 ,2 in that (1) PV shows more favourable prognosis than PNP and (2) PNP often lead to pulmonary involvement. PNP is known to associate with diverse conditions such as Non-Hodgkin's lymphomas, chronic lymphocytic leucaemia, Castleman's disease, thymoma and Waldenstrom's macroglobulinaemia; however, PV should be considered even if those possible underlying diseases for which PNP is recognised.