Perifollicular pigmentation in bullous pemphigoid: A diagnostic sign.

Sir,

One of the earliest lessons the post graduate students in dermatology learns is to clinically differentiate between pemphigus and bullous pemphigoid (BP). The differentiating points include nature of blisters—tense/flaccid, mucosal involvement, Nikolsky sign, Bulla spread sign, and tendency of the erosion to spread after rupture.[1-5] We have observed a difference in the character of repigmentation during healing stage of pemphigus and pemphigoid. In pemphigus the pigmentation is more diffuse [Figure 1], whereas in BP during the healing stage there is prominence of hair follicles which appears as tiny raised papules over the raw areas followed by follicular pigmentation [Figures 2 and 3] which subsequently becomes diffuse. We also observed that postinflammatory pigmentation is relatively more intense in BP.

Figure 1

Diffuse pigmentation in pemphigus

Figure 2

Perifollicular pigmentation

Figure 3

Perifollicular pigmentation

The diffuse pigmentation in pemphigus is possibly due to repigmentation of the intact melanocytes in the basal layer, which is not lost during the disease process. Whereas in BP, there is complete loss of epidermis with partial loss of basement membrane. Thus basal cells are lost in the disease process. Following treatment during healing phase the pigmentation has to appear either from the margin centripetally or from the appendages. Our observation suggests that the appendages play a major role in healing phase of BP and the presence of follicular pigmentation in the erosions suggests the diagnosis of bullous pemphigoid.