|LETTER TO EDITOR
|Year : 2015 | Volume
| Issue : 1 | Page : 54-55
Idiopathic eruptive macular pigmentation
Department of Dermatology, P. D. Hinduja Hospital, Mahim, Mumbai, Maharashtra, India
|Date of Web Publication||16-Jan-2015|
No. 14, Jay Mahal, A Road, Church Gate, Mumbai 400 020, Maharashtra
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Joshi R. Idiopathic eruptive macular pigmentation. Indian J Paediatr Dermatol 2015;16:54-5
It was nice reading the well written and nicely illustrated case report of idiopathic eruptive macular pigmentation (IEMP) that recently appeared in this journal.  This adds to the growing number of cases of this uncommon entity that have been reported from the Indian sub-continent in the last few years.
There are two points that need elaboration, firstly pigmented papillomatosis, which has been mentioned briefly by the authors and secondly the proposed relationship between IEMP and acanthosis nigricans, which has not been alluded to in this case report.
Pigmented papillomatosis refers to the histologic pattern of elongated dermal papillae and epidermal valleys filled with thickened basket weave stratum corneum with prominent, uniformly increased melanin in the basal layer of the epidermis. This appearance is typical of acanthosis nigricans but not specific for it, as it is also seen in epidermal nevi, some seborrheic keratoses, confluent and reticulate papillomatosis of Gougerout and Carteud and IEMP.
Pigmented papillomatosis as the diagnostic histologic finding in IEMP was first reported in 2007  and since then 5 cases of this entity have been described in Indian patients. ,,, No case report of IEMP prior to this mentions pigmented papillomatosis as a histological finding although the consensus has been that IEMP is a dermal hyper-melanosis with increased melanin in the basal layer of the epidermis. Pigmented papillomatosis appears to be the principal histological finding in all Indian cases and may be considered as an important diagnostic criterion for the diagnosis of this condition.
Idiopathic eruptive macular pigmentation presents with multiple dark brown-black discrete macules and flat plaques with velvety surface and most cases have been reported in children and adolescents. Clinically it resembles conditions like lichen planus pigmentosus, ashy dermatosis and fixed drug eruption. All the above mentioned are dermal melanoses and show numerous melanophages in the papillary dermis with or without active interface changes. IEMP by contrast is an epidermal hyper-melanosis with pigmented papillomatosis and skin biopsy is essential for the diagnosis of IEMP and its differentiation from other clinical differential diagnoses.
It has been suggested that IEMP is a variant of acanthosis nigricans , because clinically, individual lesions show a velvety surface that is reminiscent of acanthosis nigricans and histologically IEMP shares with acanthosis nigricans the finding of pigmented papillomatosis.
The classification of acanthosis nigricans has been expanded , and includes obesity associated, syndromic, acral, unilateral, generalized, familial, drug induced, malignancy associated and mixed types. All these show similar clinical findings of hyperpigmented velvety flat plaques with pigmented papillomatosis on histology, a finding similar to lesions of IEMP.
In sum, therefore, pigmented papillomatosis should be included as an important criterion for the diagnosis of IEMP and future studies should be directed to investigate the possibility of IEMP being a variant of acanthosis nigricans, to wit, eruptive acanthosis nigricans.
| References|| |
Begum A, Ramchandra BV, Kumar A. Idiopathic eruptive macular pigmentation. Indian J Paediatr Dermatol 2014;15:114-6.
Joshi R. Idiopathic eruptive macular pigmentation with papillomatosis: Report of nine cases. Indian J Dermatol Venereol Leprol 2007;73:402-5.
Grover S, Basu A. Idiopathic eruptive macular pigmentation: Report on two cases. Indian J Dermatol 2010;55:277-8.
Verma S, Thakur BK. Idiopathic eruptive macular pigmentation with papillomatosis. Indian Dermatol Online J 2011;2:101-3.
Joshi R, Palwade PK. Idiopathic eruptive macular pigmentation or acanthosis nigricans? Indian J Dermatol Venereol Leprol 2010;76:591.
Schwartz RA. Acanthosis nigricans. J Am Acad Dermatol 1994;31:1-19.
Houpt KR, Cruz PD Jr. Acanthosis nigricans. In: Freedberg IM, Eisen AZ, Wolff K, Austen KF, Goldsmith LA, Katz SI, editors. Fitzpatrick's Dermatology in General Medicine. 6 th
ed. New York: McGraw-Hill; 2003. p. 1796-801.