Idiopathic Eruptive Macular Pigmentation with Papillomatosis: An Unfamiliar Entity

Sir,

Idiopathic eruptive macular pigmentation (IEMP) is an uncommon condition characterized by the presence of asymptomatic pigmented macules that involve face, trunk, and proximal extremities in children and adolescents, which gradually resolve over months or years without any residual pigmentation or scarring. Few cases have been reported in literature. We present a case of a 20-year-old female who fulfilled all the criteria for this entity.

A 20-year-old healthy married female presented with asymptomatic brown to brownish-black lesions all over the body for 15 months. The lesions gradually increased in number and size and were stable for 6 months. The patient denied any drug intake before the development of lesions. There was no history of any preceding skin lesion. Family members were not affected. General and systemic examination revealed no abnormality.

Cutaneous examination showed multiple, round to oval hyperpigmented macules ranging from 0.5 to 2 cm over face, neck, trunk, and both extremities [Figures 1–3]. Mucosa, hair, nails, palms, and soles were within normal limits. Darier's sign was negative. The routine blood, urine, and stool examinations and thyroid function tests revealed no abnormality. Potassium hydroxide mount for fungal hyphae was negative. Biopsy from pigmented lesion on the abdomen showed acanthosis, moderate papillomatosis, and prominent melanin in the basal layer of the epidermis. The upper dermis showed sparse, perivascular infiltrate of lymphocytes with a few dermal melanophages [Figures 4 and 5]. The final diagnosis made was IEMP with papillomatosis. The patient was treated with emollients. No new lesions or change in preexisting lesions was seen at 3 months of follow-up.

Figure 1.

Multiple, round to oval hyperpigmented macules over face and neck

Figure 3.

Multiple, round to oval hyperpigmented macules over both extremities

Figure 4.

Acanthosis, moderate papillomatosis, and prominent melanin in basal layer (H and E, ×100)

Figure 5.

Upper dermis showed sparse, perivascular infiltrate of lymphocytes with a few dermal melanophages (H and E, ×400)

Figure 2.

Multiple, round to oval hyperpigmented macules over trunk

The first description was given by Degos et al. in 1978[1] in French. Sanz de Galdeano et al., in 1996,[2] summarized the criteria for diagnosis of this condition [Table 1].

Table 1.

Sanz de Galdeano et al. criteria for diagnosis idiopathic eruptive macular pigmentation

Our patient fulfilled all the criteria for this entity.

A paper describing a few Indian cases of IEMP with additional findings of acanthosis nigricans-like appearance of lesions with histological findings of pigmented papillomatosis has been described speculating IEMP to be a variant of acanthosis nigricans.[3] The lesions of our patient showed papillomatosis histologically, thus adding support to the contention that IEMP may be an eruptive variant of acanthosis nigricans.

The differential diagnosis of IEMP includes postinflammatory hyperpigmentation, fixed drug eruption, urticaria pigmentosa, lichen planus pigmentosus, and erythema dyschromicum perstans; however, the biopsy findings of epidermal hypermelanosis and the absence of either interface changes or lichenoid infiltrate or mast cell infiltrate rule out those conditions.

Papillomatosis as a histopathological finding has been only mentioned by Joshi[3] and Grover and Basu.[4] Joshi[5] reported the presence of dermal melanophages in two out of nine cases.

Our case showed both papillomatosis and dermal melanophages. However, as these findings in IEMP are not specific, biopsy is important in the diagnosis of IEMP to exclude the other conditions, which clinically resemble it.

The condition is self-limiting and has been reported to disappear spontaneously in months to years.[3] It is enticing to speculate whether IEMP is related to acanthosis nigricans; however, for pigmented papillomatosis to be regarded as diagnostic criteria, more case reports are awaited. Knowledge of this entity is important to shed further light on its pathogenesis and to familiarize physicians about IEMP.

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Conflicts of interest

There are no conflicts of interest.