Eruptive collagenoma: a rarely reported entity in Indian literature.

Eruptive collagenomas are non familial connective tissue nevi of unknown etiology presented with an abrupt onset. While most cases are reported in young adults, there is a paucity of literature in children. We report a case of a 4-year-old girl, who presented with multiple asymptomatic, papules, plaques and nodules on the face, trunk and upper extremities with no systemic involvement. Histopathologically, the lesion showed thickened homogenized collagen fibres highlighted by Masson's trichrome stain and paucity in elastic fibres by Verhoeff-van Gieson stain, confirming the diagnosis of eruptive collagenoma.

What was known?

Eruptive Collagenomas which are hamartomas of collagen, although known to occur in the first two decades of life, are usually reported in adult life, with lesions predominantly on the trunk and extremities.

Introduction

Connective tissue nevi of the skin are hamartomas, consisting predominantly from one of the components of the extracellular matrix namely collagen, elastic fibres or proteoglycans.[1] Those predominantly composed of collagen are called collagenomas. We hereby describe a case of eruptive collagenoma in a child which started at an early age of three and half years. We report this case due to its relative paucity of literature in paediatric population coupled with appearance of lesions over an atypical site (face).

Case Report

A 4 year old girl presented to the dermatology department with history of noticing multiple, grouped, asymptomatic raised skin lesions predominantly in bilateral axillae, upper back and face for 6 m. The lesions appeared on normal skin, without any preceding inflammation or trauma. There was no history of epilepsy, developmental anomalies, delay in milestones or any pertinent family history.

Clinical examination revealed multiple, symmetrically distributed, brownish papules and plaques having a leathery surface ranging in size from 0.2 × 0.2 cm [Figure 1] to 2.5 × 2.5 cm [Figure 2]. Few skin coloured, firm, non tender nodules, with surface showing irregular thickening, giving a peau d’ orange appearance were noted in the axillae [Figure 3]. No neurocutaneous stigmata, thickened nerves or systemic abnormality was detected.

Figure 1

Well defined brownish plaques having a leathery surface on flexor aspect of left forearm

Figure 2

Multiple brownish papules and plaques on the face

Figure 3

Skin coloured nodules with surface showing irregular thickening giving a peau d’ orange appearance

Considering a differential diagnosis of connective tissue nevus, Histoid Hansen's and neurofibromatosis the patient was investigated.

Routine investigations were normal, while histopathology revealed a thickened reticular dermis with haphazardly arranged thickened collagen bundles suggestive of collagen naevus on haematoxylin and eosin stain [Figure 4]. Masson's trichrome highlighted an increase in the collagen tissue in the dermis [Figure 5], while Verhoeff-van Gieson showed a marked paucity of elastic fibres [Figure 6].

Figure 4

Skin biopsy revealed thickened reticular dermis with thick and haphazardly oriented collagen bundles. (H and E, ×100)

Figure 5

Photomicrograph showing dense thick collagen bundles in the dermis. (Masson's trichrome stain, ×100)

Figure 6

Photomicrograph demonstrating an increased collagen with marked reduction in elastic fibres. (Verhoeff-van Gieson stain, ×100)

Discussion

In an attempt to classify collagenomas, Uitto et al. characterized them, based on pattern of distribution (localized or generalized) and mode of inheritance (acquired or inherited). While inherited autosomal dominant collagenomas include familial cutaneous collagenomas and shagreen's patches of Tuberous Sclerosis, those that are acquired are eruptive collagenomas and isolated collagenomas.[2]

Eruptive collagenoma, first reported by Cramer in 1966,[3] presents with sudden symmetrical appearance of several firm skin-coloured papules and nodules of various sizes, usually less than 1 cm in diameter,[4] on the trunk and upper extremities,[5] in the first two decades of life. The incidence and pathogenesis is unknown with no established family history or associated systemic findings.

Histopathologically, the lesions are characterized by an excessive accumulation of randomly arranged dense collagen bundles with either diminished, altered or absent elastic tissue.[4]

Eruptive collagenoma should be differentiated from other collagenomas namely familial cutaneous collagenoma, which is an autosomal dominated disorder, first described by Henderson et al., in 1968, characterized by clinical features similar to eruptive collagenoma. However, there is a positive family history, third decade presentation and associated systemic involvement.[6]

Isolated Collagenomas are sporadically acquired collagenomas localized to one body region and not associated with any disease.[7] They can present as paving stone naevi, plantar collagenoma, zosteriform lesions and papulolinear lesions.[8]

Shagreen patch is a collagenoma variant associated with Tuberous sclerosis, characterized by single to few asymmetrically distributed skin-coloured plaques of variable size predominantly in the lumbosacral region.[9]

Papular elastorrhexis and nevus anelasticus are closely related entities which mimic eruptive collagenomas both clinically and histologically. Papular elastorrhexis is characterised by multiple, 2 mm to 5 mm, flat, firm papules over the trunk and extremities while nevus anelasticus present as perifollicular papules. Both these conditions are associated with a decrease in elastic fibres.[10] Due to paucity of reported literature it is uncertain, whether these entities reflect a part of the same disease process or are separate disease states.

This patient was diagnosed as eruptive collagenoma based on first decade presentation of multiple lesions, histopathological findings and the absence of family history and systemic findings.

This child first presented with lesions at 31/2 years of age. Though in most cases the onset of presentation has been beyond the first decade,[511121314] only two cases have been reported with development of lesions within the first decade.[1516] The earliest onset of presentation was reported by Yahya et al.,[15] in a 2 year old Nigerian girl and the other by Lee et al.,[16] with onset at 5 years. Only 2 case reports by Mukhi et al.[12] and Yahya et al.[15] report involvement of the face in addition to other more common sites of presentation.

An extensive review of Indian literature has yielded a paucity of case reports of eruptive collagenoma. Although this entity is relatively uncommon, a good clinical acumen and a degree of suspicion help in the clinical diagnosis of such cases, while histopathology confirms the diagnosis.

What is new?

There is a relative paucity of published case reports in pediatric age group. To the best of our knowledge and after extensive review of literature, we could not find any case reports in Indian pediatric population. Besides this, involvement of atypical sites like the face is also not commonly reported.