Prurigo pigmentosa: Case series and differentiation from confluent and reticulated papillomatosis

Abstract

Prurigo pigmentosa (PP) is an uncommon, acquired inflammatory disorder with a predilection for young adults of Asian descent.1Corley S.B. Mauro P.M. Erythematous papules evolving into reticulated hyperpigmentation on the trunk: a case of prurigo pigmentosa.JAAD Case Rep. 2015; 1: 60-62Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar This condition is manifested by highly pruritic, reticulated, and erythematous papules that resolve with hyperpigmentation.2Böer A. Misago N. Wolter M. Kiryu H. Wang X.D. Ackerman A.B. Prurigo pigmentosa: a distinctive inflammatory disease of the skin.Am J Dermatopathol. 2003; 25: 117-129Crossref PubMed Scopus (113) Google Scholar Multiple cases of PP have been reported since its initial description in 1971 by Nagashima et al3Nagashima M. Ohshiro A. Schimuzu N. A peculiar pruriginous dermatosis with gross reticular pigmentation.Jpn J Dermatol. 1971; 81 ([in Japanese]): 38-39Google Scholar; however, this dermatosis is still underdiagnosed or misdiagnosed.3Nagashima M. Ohshiro A. Schimuzu N. A peculiar pruriginous dermatosis with gross reticular pigmentation.Jpn J Dermatol. 1971; 81 ([in Japanese]): 38-39Google Scholar, 4Jeunon de Sousa Vargas T. Abreu Raposo C.M. Lima R.B. Sampaio A.L. Bordin A.B. Jeunon Sousa M.A. Prurigo pigmentosa–report of 3 cases from Brazil and literature review.Am J Dermatopathol. 2017; 39: 267-274Crossref PubMed Scopus (8) Google Scholar, 5Zeng X. Li L. Cui B.N. Prurigo pigmentosa: a clinical and histopathological study of nine Chinese cases.J Eur Acad Dermatol Venereol. 2016; 30: 1794-1798Crossref PubMed Scopus (14) Google Scholar, 6Hijazi M. Kehdy J. Kibbi A.G. Ghosn S. Prurigo pigmentosa: a clinicopathologic study of 4 cases from the Middle East.Am J Dermatopathol. 2014; 36: 800-806Crossref PubMed Scopus (13) Google Scholar The most significant challenge limiting the identification of PP is successful distinction from confluent and reticulated papillomatosis (CARP). Herein, 2 patients with PP are described, with a focus on differentiating features from CARP. A 30-year-old Chinese man presented with reticulated erythematous and hyperpigmented papules on his back and shoulders (Fig 1, A and B). The eruption was present for 2 weeks and was associated with severe pruritus. Histopathologic evaluation of a punch biopsy found a subacute spongiotic dermatitis with dyskeratosis (Fig 2, A and B). After treatment with minocycline, 100 mg, and halobetasol 0.05% ointment, both twice daily for 6 weeks, the erythema and pruritus resolved, but hyperpigmentation was persistent (Fig 1, C).Fig 2A, Subacute spongiotic dermatitis with a superficial perivascular lymphohistiocytic infiltrate. B, Dyskeratosis, lymphocyte exocytosis, and Langerhans cell microabscesses are evident. (A and B, Hematoxylin-eosin stain; original magnifications: A, ×100; B, ×200.)View Large Image Figure ViewerDownload Hi-res image Download (PPT) A 31-year-old Indian man presented with a pruritic reticulated eruption on the back, chest, and chin. At the time of presentation, the eruption was present for 3 months and was composed largely of hyperpigmented papules (Fig 3, A and B). Prior treatment with topical hydrocortisone was unsuccessful. Similar to the histopathologic findings observed in patient 1, a punch biopsy found a subacute spongiotic dermatitis with necrotic keratinocytes and pigment incontinence. After treatment with minocycline, 100 mg, and halobetasol 0.05% ointment, both twice daily for 4 weeks, the papular pruritic lesions resolved, but hyperpigmentation was persistent. PP presents with a reticulated morphology, with erythema and pruritus dominating the acute stage and hyperpigmentation predominant in the chronic stage; coexistence of stages is frequent.5Zeng X. Li L. Cui B.N. Prurigo pigmentosa: a clinical and histopathological study of nine Chinese cases.J Eur Acad Dermatol Venereol. 2016; 30: 1794-1798Crossref PubMed Scopus (14) Google Scholar, 7Ilkovitch D. Patton T.J. Is prurigo pigmentosa an inflammatory version of confluent and reticulated papillomatosis?.J Am Acad Dermatol. 2013; 69: e193-195Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar CARP is also manifested by hyperpigmented papules with a netlike appearance and a predilection for the trunk and proximal extremities.8Lim J.H. Tey H.L. Chong W.S. Confluent and reticulated papillomatosis: diagnostic and treatment challenges.Clin Cosmet Investig Dermatol. 2016; 9: 217-223Crossref PubMed Scopus (23) Google Scholar PP and CARP have overlapping clinical morphology, and PP may be clinically diagnosed as CARP given the rarity of the former compared with the latter diagnosis.7Ilkovitch D. Patton T.J. Is prurigo pigmentosa an inflammatory version of confluent and reticulated papillomatosis?.J Am Acad Dermatol. 2013; 69: e193-195Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar Recently, a case was reported with features of both PP and CARP, suggesting that these conditions may represent a spectrum rather than separate entities.7Ilkovitch D. Patton T.J. Is prurigo pigmentosa an inflammatory version of confluent and reticulated papillomatosis?.J Am Acad Dermatol. 2013; 69: e193-195Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar However, distinction is facilitated by demographic information, clinical morphology in the acute stage of PP, histopathology, treatment outcomes, and prognosis. These differentiating features are summarized in Table I.Table IDifferentiation of PP from CARP5Zeng X. Li L. Cui B.N. Prurigo pigmentosa: a clinical and histopathological study of nine Chinese cases.J Eur Acad Dermatol Venereol. 2016; 30: 1794-1798Crossref PubMed Scopus (14) Google Scholar, 6Hijazi M. Kehdy J. Kibbi A.G. Ghosn S. Prurigo pigmentosa: a clinicopathologic study of 4 cases from the Middle East.Am J Dermatopathol. 2014; 36: 800-806Crossref PubMed Scopus (13) Google Scholar, 7Ilkovitch D. Patton T.J. Is prurigo pigmentosa an inflammatory version of confluent and reticulated papillomatosis?.J Am Acad Dermatol. 2013; 69: e193-195Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar, 8Lim J.H. Tey H.L. Chong W.S. Confluent and reticulated papillomatosis: diagnostic and treatment challenges.Clin Cosmet Investig Dermatol. 2016; 9: 217-223Crossref PubMed Scopus (23) Google Scholar, 9Min Z.S. Tan C. Xu P. Zhu W.Y. Confluent and reticulated papillomatosis manifested as vertically rippled and keratotic plaques.Postepy Dermatol Alergol. 2014; 31: 335-337Crossref PubMed Scopus (5) Google ScholarDemographicClinical morphologySymptomsHistologyTreatmentPrognosisPPMost common in Asian patients and dark-skinned races; rare in whitesAcute: papular, vesicular, or urticarial erythematous eruption with reticulated appearance on chest and backChronic: reticulated hyperpigmentationSevere pruritus ± burning sensation in acute stageAcute: acute or subacute spongiosis with dyskeratosis ± subcorneal or intraepidermal pustulesChronic: pigment incontinence and sparse dermal lymphocytic infiltrateMinocycline, doxycycline, tetracycline, dapsone, topical steroidsAcute findings of pruritus and papular or vesicular lesions resolve with treatment; hyperpigmentation persists for months to yearsCARPOccurs in all ethnicities including whitesScaly, hyperpigmented papules with central confluence and peripheral reticulation on the chest, back, neck, axillae, and occasionally proximal extremitiesAsymptomatic in majority; when present, pruritus is mildHyperkeratosis, papillomatosis, basilar hyperpigmentation, follicular plugging, flattening of rete ridgesMinocycline, doxycycline, azithromycin, erythromycin, isotretinoin, topical tretinoin, tazarotene, topical steroidsChronic course with frequent recurrence after discontinuation of therapy; no persistent dyspigmentationCARP, Confluent and reticulated papillomatosis; PP, prurigo pigmentosa. Open table in a new tab CARP, Confluent and reticulated papillomatosis; PP, prurigo pigmentosa. Compared with PP, CARP also occurs in dark-skinned patients but is more common in white patients, with presentation between the ages of 8 and 32 years and a male-to-female ratio of 1.4 to 2.6:1.8Lim J.H. Tey H.L. Chong W.S. Confluent and reticulated papillomatosis: diagnostic and treatment challenges.Clin Cosmet Investig Dermatol. 2016; 9: 217-223Crossref PubMed Scopus (23) Google Scholar In contrast, PP is more common in Asian patients, particularly those from China and Japan, affects females more often than males (4-6:1), and usually presents in individuals in their 20s.1Corley S.B. Mauro P.M. Erythematous papules evolving into reticulated hyperpigmentation on the trunk: a case of prurigo pigmentosa.JAAD Case Rep. 2015; 1: 60-62Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar, 5Zeng X. Li L. Cui B.N. Prurigo pigmentosa: a clinical and histopathological study of nine Chinese cases.J Eur Acad Dermatol Venereol. 2016; 30: 1794-1798Crossref PubMed Scopus (14) Google Scholar, 6Hijazi M. Kehdy J. Kibbi A.G. Ghosn S. Prurigo pigmentosa: a clinicopathologic study of 4 cases from the Middle East.Am J Dermatopathol. 2014; 36: 800-806Crossref PubMed Scopus (13) Google Scholar CARP shows central confluence and peripheral reticulation and is composed of hyperpigmented scaly papules, sometimes with an ichthyosiform appearance. The preferred sites of involvement are the upper trunk (particularly the interscapular and intermammary skin), neck, and axillae.7Ilkovitch D. Patton T.J. Is prurigo pigmentosa an inflammatory version of confluent and reticulated papillomatosis?.J Am Acad Dermatol. 2013; 69: e193-195Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar In contrast, PP evolves from initially erythematous papules or papulovesicles into hyperpigmented macules later. Although the chest and back are similarly involved in PP and CARP, PP tends to spare the neck and axillae.1Corley S.B. Mauro P.M. Erythematous papules evolving into reticulated hyperpigmentation on the trunk: a case of prurigo pigmentosa.JAAD Case Rep. 2015; 1: 60-62Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar, 2Böer A. Misago N. Wolter M. Kiryu H. Wang X.D. Ackerman A.B. Prurigo pigmentosa: a distinctive inflammatory disease of the skin.Am J Dermatopathol. 2003; 25: 117-129Crossref PubMed Scopus (113) Google Scholar, 8Lim J.H. Tey H.L. Chong W.S. Confluent and reticulated papillomatosis: diagnostic and treatment challenges.Clin Cosmet Investig Dermatol. 2016; 9: 217-223Crossref PubMed Scopus (23) Google Scholar Although PP is associated with significant and often severe pruritus, most patients with CARP are asymptomatic.2Böer A. Misago N. Wolter M. Kiryu H. Wang X.D. Ackerman A.B. Prurigo pigmentosa: a distinctive inflammatory disease of the skin.Am J Dermatopathol. 2003; 25: 117-129Crossref PubMed Scopus (113) Google Scholar, 8Lim J.H. Tey H.L. Chong W.S. Confluent and reticulated papillomatosis: diagnostic and treatment challenges.Clin Cosmet Investig Dermatol. 2016; 9: 217-223Crossref PubMed Scopus (23) Google Scholar, 9Min Z.S. Tan C. Xu P. Zhu W.Y. Confluent and reticulated papillomatosis manifested as vertically rippled and keratotic plaques.Postepy Dermatol Alergol. 2014; 31: 335-337Crossref PubMed Scopus (5) Google Scholar Histologically, CARP is characterized by hyperkeratosis, papillomatosis, and basilar pigmentation—the findings of acanthosis nigricans. In contrast, PP shows spongiosis with vesiculation, dyskeratosis, and sometimes subcorneal or intraepidermal neutrophilic abscesses in its acute stage. Vacuolar change is infrequent. A chronic stage is characterized by a sparse perivascular lymphohistiocytic infiltrate with marked pigment incontinence. Analogous to the clinical findings of PP, the histologic stages may overlap.2Böer A. Misago N. Wolter M. Kiryu H. Wang X.D. Ackerman A.B. Prurigo pigmentosa: a distinctive inflammatory disease of the skin.Am J Dermatopathol. 2003; 25: 117-129Crossref PubMed Scopus (113) Google Scholar, 7Ilkovitch D. Patton T.J. Is prurigo pigmentosa an inflammatory version of confluent and reticulated papillomatosis?.J Am Acad Dermatol. 2013; 69: e193-195Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar, 9Min Z.S. Tan C. Xu P. Zhu W.Y. Confluent and reticulated papillomatosis manifested as vertically rippled and keratotic plaques.Postepy Dermatol Alergol. 2014; 31: 335-337Crossref PubMed Scopus (5) Google Scholar The first-line therapy for both PP and CARP is minocycline. Second-line treatments for CARP include macrolide antibiotics, such as azithromycin, whereas dapsone may be used as an alternative for PP. Antibiotics are useful in both diseases because of their anti-inflammatory properties, possibly relating to inhibition of neutrophil migration and oxygen release.1Corley S.B. Mauro P.M. Erythematous papules evolving into reticulated hyperpigmentation on the trunk: a case of prurigo pigmentosa.JAAD Case Rep. 2015; 1: 60-62Abstract Full Text Full Text PDF PubMed Scopus (7) Google Scholar, 9Min Z.S. Tan C. Xu P. Zhu W.Y. Confluent and reticulated papillomatosis manifested as vertically rippled and keratotic plaques.Postepy Dermatol Alergol. 2014; 31: 335-337Crossref PubMed Scopus (5) Google Scholar In CARP, topical tretinoin and tazarotene and oral isotretinoin have been used in minocycline-refractory cases.8Lim J.H. Tey H.L. Chong W.S. Confluent and reticulated papillomatosis: diagnostic and treatment challenges.Clin Cosmet Investig Dermatol. 2016; 9: 217-223Crossref PubMed Scopus (23) Google Scholar Topical corticosteroids are of limited efficacy in CARP and PP but may be used as adjunctive treatment for pruritus in PP.5Zeng X. Li L. Cui B.N. Prurigo pigmentosa: a clinical and histopathological study of nine Chinese cases.J Eur Acad Dermatol Venereol. 2016; 30: 1794-1798Crossref PubMed Scopus (14) Google Scholar, 6Hijazi M. Kehdy J. Kibbi A.G. Ghosn S. Prurigo pigmentosa: a clinicopathologic study of 4 cases from the Middle East.Am J Dermatopathol. 2014; 36: 800-806Crossref PubMed Scopus (13) Google Scholar, 7Ilkovitch D. Patton T.J. Is prurigo pigmentosa an inflammatory version of confluent and reticulated papillomatosis?.J Am Acad Dermatol. 2013; 69: e193-195Abstract Full Text Full Text PDF PubMed Scopus (8) Google Scholar Although the acute lesions of PP subside after treatment, leaving residual hyperpigmentation that persists for months to years, CARP is characterized by a chronic course with recurrences after discontinuation of therapy. However, once resolution of scaling papules is achieved in CARP, persistent hyperpigmentation is not characteristic.8Lim J.H. Tey H.L. Chong W.S. Confluent and reticulated papillomatosis: diagnostic and treatment challenges.Clin Cosmet Investig Dermatol. 2016; 9: 217-223Crossref PubMed Scopus (23) Google Scholar, 9Min Z.S. Tan C. Xu P. Zhu W.Y. Confluent and reticulated papillomatosis manifested as vertically rippled and keratotic plaques.Postepy Dermatol Alergol. 2014; 31: 335-337Crossref PubMed Scopus (5) Google Scholar PP and CARP are both acquired dermatoses of unknown etiology that affect young adults, present with reticulated papules distributed on the trunk, and respond quickly to treatment with minocycline. Discrimination is permitted by attention to demographics, morphology in early or acute disease, histopathologic findings, and the presence or absence of persistent hyperpigmentation after treatment.