Multiple Hypopigmented Truncal Papules.

A 21-year-old male presented with multiple asymptomatic hypopigmented lesions over the back and front of trunk, which have been persisting unaltered as regards their physical appearance or number since he first developed these at 5 years of age. There was no history of any other skin abnormalities before the age of 5 or any systemic complaints. He reported no significant family history. General physical examination revealed no abnormality. Cardiovascular examination and electrocardiogram were within normal limits. Dermatological examination of the trunk revealed multiple pale white, fibrotic, rubbery, non-tender papules and nodules ranging from 5 mm to 1 cm in diameter with highest concentration over the lower back [Figures 1a and b]. There was no evidence of lesions elsewhere on the body. Histopathological examination of the papule revealed areas with thick and haphazardly-oriented collagen bundles within the reticular dermis [Figure 2]. The collagen was strongly stained with Masson trichrome stain showing an intense blue-green color [Figure 3]. The Van Gieson stain for elastin showed few fragmented interspersed elastin fibers.

Figure 1

(a) Multiple hypopigmented papules and plaques over trunk. (b) Hypopigmented fibrotic papules over the abdomen

Figure 2

Histopathology showing thickened dermis with increased and haphazardly-oriented collagen bundles. (H and E stain, ×40)

Figure 3

Dermis showing dense coarse collagen bundles (Masson trichrome stain, ×100)

Question

What is the diagnosis?

Answer

Eruptive Collagenomas

Discussion

Connective tissue nevi are acquired dermal connective tissue hamartomas characterized predominantly by an imbalance in the relative amount and distribution of collagen, elastin, or proteoglycans. Eruptive collagenomas form a part of the spectrum of connective tissue nevi and are predominantly composed of collagen.[12] Uitto et al. proposed a classification for connective tissue nevi based on clinical, genetic, and histopathologic considerations. According to their classification, hamartomas of the collagen type or ’collagenomas’ can be inherited (familial cutaneous collagenoma (FCC), shagreen patches in tuberous sclerosis) or acquired (eruptive collagenomas, isolated collagenoma).[13]

Cramer first described eruptive collagenomas in 1966.[145] However, Smith and Bernstein reported the first case in English literature in 1978.[6] Since then only a dozen such other cases have been reported.[1236] Eruptive collagenomas are characterized by sudden appearance of multiple white to skin colored papules or nodules of variable sizes usually less than 1 cm over the trunk and arms. This non-familial entity has an equal sex distribution and usually develops during the first decade of life.[12] The underlying pathogenesis to this condition has not been understood; however, it has been known to be associated with multiple endocrine neoplasia type 1 and Proteus syndrome.[7] Histopathology reveals dense bundles of collagen with absent or decreased, partially fragmented elastic fibers.[126] This decrease in elastin possibly represents a ’dilution phenomenon’ related to the excessive amount of collagen.[2] Scanning electron microscopy of the dermis shows individualized collagen fibers forming waved compact masses resembling noodles rather than bundles characteristic of dermal collagen. Further transmission electron microscopy shows sparse and loose collagen fibers with variable diameters in cross sections.[7] No successful therapeutic options have been reported, and the lesions have persisted in all patients.

Similar clinical and histopathological features are also seen in familial cutaneous collagenoma (FCC), a condition with an autosomal dominant mode of inheritance where the lesions are mostly confined to the upper two-thirds of the back and usually appear during adolescence.[28] It may also be associated with underlying cardiac abnormalities in particular idiopathic progressive cardiomyopathy with congestive cardiac failure and early ’R’-wave transition in a few patients.[6]

The shagreen patch of tuberous sclerosis too is histologically similar to the collagenoma of FCC, but usually occurs as a single lesion over the lumbosacral area.[2]

We consider this case of ours to be of eruptive collagenomas due to the abrupt onset of lesions, negative family history and absence of any related cardiac illness. Similar clinical features as above, and the focal absence of elastic fibers in nevus anelasticus, papular elastorrhexis, and eruptive collagenomas suggest that these three rare, non-familial conditions represent a single disease or disease spectrum.[12]