Answer of Dermatopathology Case 78

Pustular Psoriasis

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Abstracts:

The histopathological spectrum of acute generalized exanthematous pustulosis (AGEP) and its differentiation from generalized pustular psoriasis. J Cutan Pathol. 2010 Dec;37(12):1220-9.

BACKGROUND: Acute generalized exanthematous pustulosis (AGEP) represents a severe, acute, pustular skin reaction that is most often induced by drugs. AGEP can be difficult to differentiate from generalized pustular psoriasis (GPP) both clinically and histopathologically. We present a systematic description of the histopathological spectrum of AGEP and GPP with a focus on discriminating features.
MATERIALS AND METHODS: A retrospective, descriptive, comparative histopathological study was completed utilizing step sections of 43 biopsies of 29 cases with a validated diagnosis of probable or definite AGEP and 24 biopsies of 19 cases with an established diagnosis of GPP.
RESULTS: In AGEP, biopsies from erythema and pustules showed minor differences, whereas histopathology of the acute stage of GPP showed major differences compared to the chronic stage. Comparing AGEP and GPP, the presence of eosinophils, necrotic keratinocytes, a mixed interstitial and mid-dermal perivascular infiltrate and absence of tortuous or dilated blood vessels were in favor of AGEP. Moreover, chronic GPP was characterized by prominent epidermal psoriatic changes. The frequency of a psoriatic background of AGEP patients in our study was higher than that of psoriasis in the general population. However, histopathology of a subgroup of AGEP patients with a personal history of psoriasis revealed no significant differences from the other AGEP patients.
CONCLUSIONS: The spectrum of histopathological features of both AGEP and GPP is presented. Despite considerable overlap, subtle consistent histopathological differences and the grade of severity of specific features can help in differentiation. We could neither substantiate earlier reports that follicular pustules exclude AGEP nor did we see vasculitis as a specific feature in AGEP. Our study also supports the concept that AGEP is a separate entity that is distinct from GPP.

A comparison of Ki-67 antigen presentation in acute generalized exanthematous pustulosis and pustular psoriasis. Arch Dermatol Res. 2010 Sep;302(7):525-9. Epub 2010 Mar 25.

Ki-67 is an established marker of cell proliferation. It is highly expressed in psoriasis and correlated with the clinical severity of psoriasis. Higher number of Ki-67 positive keratinocytes has been observed in pustular psoriasis (PP) as compared with psoriasis vulgaris. As for Acute generalized exanthematous pustulosis (AGEP), a distinct disease entity but similar in many aspects of clinicopathologic features to PP, Ki-67 immunostaining presentation has never been investigated before. This study aimed to compare Ki-67 immunostaining presentation between PP and AGEP. By immunohistochemical staining, we compared Ki-67 immunostaining presentation on skin lesions of five patients of AGEP and five age-matched patients of PP. Ki-67 positive keratinocytes were counted and mean values were determined to compare between PP and AGEP. An augmented presence of Ki-67 positive keratinocytes was found in both AGEP and PP and they distributed not only in basal cell layer but in middle or even upper part of epidermis. Statistical analysis using Mann-Whitney U test showed no difference of epidermal proliferation rate between the two groups (P = 0.222). The results showed there was no difference of Ki-67 immunostaining presentation between AGEP and PP. Besides, we found marked increase of Ki-67-positive proliferating keratinocytes in AGEP and suggested that epidermal hyperproliferation may also play an important role in the formation of AGEP. We also discussed the possible pathophysiology of AGEP, possible epidermal architecture changes in AGEP and PP, and found the similarity in pathophysiology of AGEP and PP.

Generalized pustular psoriasis of pregnancy successfully treated with cyclosporine. Indian J Dermatol Venereol Leprol. 2009 Nov-Dec;75(6):638.

Two multigravidae aged 27 and 29 years, with previous uneventful pregnancies, second being psoriatic, reported at 24 and 28 weeks of pregnancies, with generalized pustular lesions. Laboratory findings, including serum calcium were normal. Ultrasonography showed normal fetal growth. Histopathology confirmed pustular psoriasis. Patients were put on cyclosporine 3 mg/ kg weight/ day after failure of an initial systemic steroid. Blood pressure, pulse, and fetal heart sounds were recorded every 12 hours, and ultrasonography and blood parameters, biweekly. Cyclosporine was tapered and stopped after delivery of two healthy babies at 38 weeks. We conclude that cyclosporine can be an option in the management of pustular psoriasis of pregnancy or psoriasis with pustulation in pregnancy.