# Pustular psoriasis: From Pathophysiologyology to Treatment
### Clinical Variants
#### 2.1.3 Annular Pustular Psoriasis
Recurrences with subsequent pregnancies are frequent, sometimes with earlier onset and greater severity, and can also occur while on treatment with oral contraceptives [33; 39; 40]. * Annular Pustular Psoriasis
* Circinate or annular PP is a rare variant, consisting in an erythematous eruption with annular or polycyclic lesional morphology, small sterile pustules at the periphery of the lesions, and fine desquamation with mild-to-no systemic symptoms. Usual sites of involvement are flexural areas of the trunk and proximal extremities, buttocks and abdomen [41]. Formerly included within the spectrum of GPP, it is now considered a \begin{table}
\begin{tabular}{p{142.3 pt} p{284.5 pt}} \hline \hline Main features of AGEP & Rare disorder attributed mostly to drugs (infections, hypersensitivity to mercury and spider bite have sporadically been implicated) \\ Main features & Sudden occurrence of a generalized skin rash with sterile nonfollicular pinhead-sized pustules on an oedematous erythema, often associated with systemic symptoms, including fever, leucocytosis and neutrophil \\  & Spontaneous resolution of pustules within a few days followed by pin-point desquamation \\  & Mild, nonerosive mucous membrane involvement (mostly oral) in about 20\% of cases \\ \hline  & Absence of family/personal history of psoriasis (however, history of psoriasis possible in AGEP) \\  & Recent drug administration (very frequent in AGEP, possible but less frequent in GPP, that can also be drug-elicited) \\  & Predominance of lesions in the folds, especially at the onset \\  & Shorter duration of fever and pustules \\  & Spontaneous rapid resolution (within 15 days after withdrawal of the culprit drugs) and \\  & nonrecurrent tendency \\ Factors favoring the diagnosis of AGEP & Arthritis (rare in AGEP, affecting about 30\% of cases in GPP) \\  & over GPP & Peripheral eosinophil (present in about one-third of cases and usually mild) \\  & Histopathological features: \\  & - & superficial spongiform pustules, exocytosis of neutrophils and eosinophils, occasional necrotic keratinocytes, papillary dermal oedema, mixed dermal infiltrates containing neutrophils and \\  & - & presence of eosinophils, absence of PDCs and absence of tortuous dilated capillaries favoring a diagnosis of AGEP over PP (perivascular and intraepidermal PDCs, dilated tortuous vessels and MxA expression in the dermal inflammatory infiltrate significantly in favor of PP) \\ \hline \hline \end{tabular}  
* Von Zumbusch psoriasis may exhibit an unfavourable prognosis, especially in cases evolving from ACH [1; 29]. Mortality in GPP has mostly been attributed to complications resulting from sepsis, acute respiratory distress syndrome and cardiac failure [14]. Secondary amyloidosis is mentioned as another potential complication of GPP [30].
* Impertigo Herpetiformis (Pustular Psoriasis of Pregnancy)
* IH is a form of pregnancy-associated PP first described in 1872 by [PERSON] [31]. It is controversial whether this entity should be considered distinct from PP [32; 33]. It is most frequently observed in the last trimester of pregnancy [34]. Multiple sterile pustules on an erythematous base are observed in an annular configuration at the folds with subsequent spreading over the body [34; 35]. Systemic symptoms, such as fever, chills, fatigue, nausea, diarrhea, and polyarthalgias, may be observed [32; 33; 34]. Leukocytosis with neutrophic predominance, anemia, increased erythrocyte sedimentation rate, hypoclcemia, hypophosphatemia and hypoalbuminemia are notable laboratory findings [35; 33]. IH, especially if severe and long-lasting, may lead to poor neonatal outcomes, including placental insufficiency, fetal abnormalities, stillbirth, and early neonatal death [36], as well as to maternal death [31]. Most patients experience prompt remission in the post-partum period [37; 38]. Recurrences with subsequent pregnancies are frequent, sometimes with earlier onset and greater severity, and can also occur while on treatment with oral contraceptives [33; 39; 40].  
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