A Case Report of Inflammatory Disseminated Superficial Porokeratosis: An Eruptive Pruritic Papular Variant of Porokeratosis

Ling-Ling Luo, Hao Chen, Xue-Si Zeng, Pan-Gen Cui,

1Department of Dermatology, 2Department of Pathology, Hospital for Skin Diseases (Institute of Dermatology), Chinese Academy of Medical Sciences and Peking Union Medical College, Nanjing, Jiangsu 210042, China.

Abstract Introduction:Eruptive pruritic papular porokeratosis(EPPP)is a rare variant of porokeratosis.Several cases of this varient of porokeratosis had been reported.Here, we reported an old man with this rare kind of porokeratosis which is often eruptive and pruritic.Case report:A 72 years-old Chinese man presented to our hospital with intensively pruritic papular lesions on his trunk and limbs.Physical examination showed numerous scattered keratotic papules measuring 35mm in diameter on his trunk and extremities.Some coalesced into anannular lesion with a slightly raised peripheral red rim.A tissue biopsy revealed the presence of a cornoid lamella.The patient was diagnosed with EPPP.After 3-months’ treatment of antihistamines and topical steroid agents, the lesions and the pruritus were diminished.Discussion:EPPP predominantly happens in an old male demographic.Patients with EPPP often develop pruritic papules spread on the body with or without preexisting typical porokeratosis lesions,and the lesions can subside within few months, leaving small brown spots or annular lesions.EPPP has the unique histological characteristic of porokeratosis cornoid lamella.The mechanism of EPPP is still unknown.It is important for clinicians to be aware of a disseminated pruritic papules as a manifestation of EPPP.Conclusion:The lesion of porokeratosis can be manifested as eruptive papules with intensive itch.When a patient develops eruptive pruritic papules,it is necessary to consider the possibility of EPPP.Histopathology is necessary for diagnosis.

Keywords: porokeratosis, pruritus, case report

Introduction

Porokeratosis is an uncommon, chronic epidermal keratinization disorder clinically characterized by annular keratotic lesions with a slightly elevated defined ridge and the histological feature of a cornoid lamella(ie, a column of parakeratotic cells).Common clinical variants of porokeratosis include porokeratosis of Mibelli, disseminated superficial porokeratosis(DSP),disseminated superficial actinic porokeratosis, porokeratosis palmaris et plantaris disseminata, linear porokeratosis, and porokeratosis ptychotropica.Other rare variants of porokeratosis have also been reported,such as facial porokeratosis,giant porokeratosis, punched-out porokeratosis, hypertrophic verrucous porokeratosis,reticulate porokeratosis,eruptive pruritic papular porokeratosis (EPPP), and porokeratosis ptychotropica.Among these, DSP, which is usually asymptomatic,is characterized by numerous small annular lesions that are spread over the whole body.Cases of unusual pruritic porokeratosis have recently been reported under various names such as inflammatory DSP, inflammatory stage of DSP,and EPPP.EPPP is recognized as an unusual variant of DSP.Only a few cases of this uncommon DSP variant have been reported in the English-language literature.We herein describe a 72-year-old Chinese man with this variant of pruritic porokeratosis.

Case report

A 72-year-old man presented to our hospital with an 8-month history of sudden-onset, intensively pruritic papular lesions on his trunk and limbs.The lesions had first appeared on his chest 8 months previously with no apparent trigger.The patient had been treated with unknown topical agents at a local hospital,but the clinical symptoms did not improve.The eruption gradually spread to his whole body.He was then referred to us for further examination.Physical examination revealed hundreds of sharply demarcated keratotic papules measuring 3–5mm in diameter scattered on his trunk and extremities(Fig.1A and 1B).Some of the papules ad coalesced into an annular lesion with a slightly raised peripheral red rim.No lesions were found on the palms, soles, face, or mucosa.The patient had no history of systemic disease or underlying immune suppression and no pre-existing skin disease.His family history and psycho-social history were unremarkable.

Figure 1. Clinical features and histopathology of the patient with inflammatory disseminated superficial porokeratosis.A:Red-to-brown papules on the legs.B:Red keratotic papules scattered on the trunk,some of which had coalesced into annular lesions with a slightly raised peripheral red rim.C: Histopathology of a lesion shows a cornoid lamella (hematoxylin-eosin, ×800).

Laboratory examination revealed elevated concentrations of aspartate transaminase(79U/L),alanine transaminase(54U/L),cholesterol(6.71mmol/L),and low-density lipoprotein (5.0mmol/L).The complete blood count was normal.A tissue biopsy was taken from his right leg and showed the presence of a cornoid lamella and hyperkeratosis (Fig.1C).A predominantly perivascular infiltrate of lymphocytes was present in the superficial layer of the dermis.Crystal violet, van Gieson, and elastic fiber staining results were negative.There was an appropriate exclusion of darier’s disease, pityriasis rubra pilaris,primary cutaneous amyloidosis and perforating diseases.

The patient was diagnosed with EPPP based on clinical manifestations and histopathological and laboratory findings.He was treated with ebastine at 10mg once a day and ketotifen eumarate at 1mg once a day,respectively, and topical steroid agents.After a 3-month follow-up period,the pruritic papules had become smaller and the pruritus was diminished but not eliminated.No adverse event was presented.The patient gave his agreement for the case publication.

Discussion

Kanzakiet al.1first described three cases of an unusual variant of porokeratosis in 1992 and designated this kind of porokeratosis as EPPP.All patients with EPPP have three clinical features in common:they have had a history of asymptomatic DSP for several years,they then suddenly develop intensively pruritic papules over the whole body,and the lesions subside within few months, leaving small brown spots or annular lesions.Another patient with similar clinical features was reported by Tanakaet al.2in 1995,and the authors termed the condition“inflammatory DSP.” Inflammatory porokeratosis predominantly occurs in an older demographic, and the male:female ratio is 2:1.3A previous summary indicated that inflammatory changes can take place with or without the presence of preexisting typical porokeratosis lesions;histologically,the cornoid lamella of inflammatory DSP is smaller or shallower than that of typical porokeratosis,which is consistent with our case;and the inflammatory lesions may disappear within several months, leaving brown macular or annular lesions in a mean period of 3.3 months.4

The peripheral expansion of clones of mutant epidermal keratinocytes caused by dysfunction of immune mechanisms is believed to contribute to the development of porokeratosis.5The development of porokeratosis has been reported in patients with immunosuppression due to systematic diseases, tumors, or drugs.6According to one report,the lesions of DSP in a patient with paraneoplastic dermatomyositis developed during systematic steroid therapy and resolved after the steroid was stopped,7indicating that immune reactions play a key role in the process of porokeratosis.

However, the etiology of inflammatory DSP is unclear.Kanzakiet al.1noted that if similarity exists in the etiology between inflammatory DSP and verruca plana, which often show pruritic inflammatory changes in a spontaneous regression process, immunological reactions against neoplastic keratinocytic clones in porokeratosis may result in inflammation in patients with inflammatory DSP.Additionally, infiltration of eosinophils into the lesion may be the cause of the pruritus.However, whether pruritic inflammatory changes occur in these patients is not certain.

Histologically,colloid bodies and amyloid deposits can be detected in the skin biopsy specimens from patients with a spontaneous process.The colloid bodies in the dermis are considered to result from the destruction of abnormal keratinocytic clones in the epidermis.Amyloid materials stain positive for 34BE12, which indicates that the origin of the amyloid is degenerating epidermal keratinocytes.8Both the colloid bodies and the amyloid deposits are believed to be associated with complete DSP remission.

Moreover, immunohistological examination in some cases shows a number of CD3+, CD4+, and CD8+lymphocytes and CD45RO+, CLA+, and HLA-DR+inflammatory cells, suggesting that activated memory T cells have an important role in the etiology.8Tanakaet al.2reported the presence of CD8+cells and predominant CD4+T cells and CD1a+Langerhans cells in the dermis of a pruritic inflammatory lesion and presumed that a T-cellmediated immune reaction against abnormal clones in the epidermis plays a crucial role in the regression of multiple porokeratosis lesions.Another report compared infiltration of different cells in the dermis in various cases and postulated that CD8+T cells might be important in the spontaneous regression process of the uncommon variant of DSP.9

In conclusion,since the first report of EPPP in 1992,19 patients with this disease, including ours, have been described in the English-language literature.Although the pathological mechanism of the pruritus and spontaneous regression remains unknown,an immunological response to clones of mutant keratinocytes has been considered to play a key role in inflammatory DSP.There is no consensus about the optimal treatment of inflammatory DSP.In the present case, we adopted antihistamines and topical steroids,which resulted in limited improvement.Whether the lesions will spontaneously resolve requires further follow-up.Accumulation of more case reports of this unusual kind of pruritic porokeratosis is needed to clarify the underlying mechanism.