INTRODUCTION
The pathologic, dermoepidermal reactive phenomenon incited by exogenous substances or altered dermal constituents is called “Transepidermal elimination” (TEE). It is characterized by formation of multiple transepithelial perforating channels, facilitating extrusion of altered dermal material/foreign substances to the exterior.[1] There are four TEE disorders 1. Reactive perforating collagenosis (RPC) 2. Elastosis perforans serpiginosa (EPS) 3. Perforating folliculitis (PF) and Kyrle disease (KD), these four share common features of elimination of altered dermal components through epidermis.[2]
CASE REPORT
A 52 year old married female, came with multiple, itchy, red raised lesions over the lower back since one month. There was gradual increase in size and number. There was no prior trauma/insect bite. She had not taken treatment for the same. She was a known case of diabetes mellitus, hypertension and bronchial asthma since 10 years on treatment. Cutaneous examination revealed multiple, round, well defined, erythematous to hyperpigmented papules and plaques with central adherent crusting over lower back [Figure 1]. Other mucocutaneous examination was normal. Histopathology showed cup shaped depression of epidermis filled with plug consisting of altered collagen and adjacent acanthotic epidermis with overlying hyperkeratosis and collarette parakeratosis. Epidermis underlying the depression was thin with fine slits through which vertically oriented basophilic collagen fibers were extruded. Upper dermis showed mild perivascular lymphocytic infiltrate (Figure 2a H&E 4x Figure 2b H&E 40x) - Diagnosis of ARPC was made on clinicopathological correlation and she was started on potent topical steroids with good improvement.
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Figure 1: Multiple bilaterally symmetrically, distributed well defined, erythematous to hyperpigmented papules and plaques with central adherent crusting on lower back
Figure 2: 2a and 2b (H&E 4X, 40X).: Cup-shaped epidermal invagination filled with keratotic plug consisting of degenerated collagen, parakeratotic cells and cellular fragments
DISCUSSION
Mehregan et al. in 1967 first reported RPC,[3] which is a rare form (few cases reported) of TEE, in which altered collagen is genetically extruded through the epidermis.[3] It includes inherited and acquired (ARPC) types, triggering factors include minor trauma, arthropod bites, scabies and scratching in ARPC.[2]
Diagnostic criteria for ARPC proposed by Faver et al. include[3]
- Transepidermal elimination of dermal connective tissue material.
- Keratotic plug at the center of umbilicated papules or nodules.
- Age of onset after 18 years.
Several studies have identified the potential association of diabetic microangiopathy with ARPC, patients with micro vasculopathy being highly susceptible to the disease.[3,4]
Patients with type 2 diabetes mellitus develop microvascular diseases leading to intense pruritus. Repeated microtrauma caused by scratching may cause necrosis in the connective tissue fibers of the dermis, resulting in TEE. There is also epithelial cell hyperplasia, motivating an inflammatory foreign body reaction to altered collagen. In diabetics levels of fibronectin (influence cell differentiation and migration) are increased in plasma and skin where perforating lesions appear. Fibronectin is associated with type IV collagen fibers and keratinocytes causing epithelial cell hyperplasia, thereby triggering onset of perforating injuries.[2,4] Immunoreactivities of transforming growth factor-b3, matrix metalloproteinase (MMP)-1 and tissue inhibitor of metalloproteinase-1 have been found to be increased in the lesions of ARPC.[5]
Hypoxic state may cause the separation of collagen and disruption of inter keratinocyte. Hence it is thought that diabetic microvasculopathy and the resultant hypoxic state in dermis may be a predisposing factor of ARPC.[3]
The classic lesions are isolated pruritic papules, which develop gradually from pinpoint size to 5 to 6 mm in diameter, with keratotic plugs in the center which are not easy to remove and can leave behind atrophic scars and temporary hypochromic areas.[3,4,5] Koebner phenomenon is not reported in most of the cases. The extensor surfaces of limbs are more commonly affected, but trunk and face may be involved, back being the uncommon site.[6]
Lesions are usually self-healing in 6 to 8 weeks without any therapy, but often recur.[2]
Systemic lupus erythematous, vasculitis, dermatomyositis and malignancies like lymphoma, thyroid carcinoma and breast carcinoma, are also reported as coexisting diseases.[2]
Histopathology is diagnostic. In the early period, lesions show hyperplasia, thickening of epidermis and widening of papillary dermis, with degenerated collagen bundles. In the later period, cupshaped epidermal invagination filled with keratotic plug consisting of degenerated collagen, parakeratotic cells and cellular fragments can be seen. Necrotic basophilic collagen fibers are eliminated to the epidermis.[2,4] Recently, dermoscopy is recommended as a useful and quick diagnostic aid since its diagnostic accuracy is comparable to histopathology.[3]
In the early stages the differential diagnosis includes amyloidosis and vasculitis. Late lesion needs to be distinguished from elastosis perforans serpiginosa, peforating folliculitis, Kyrle's disease and perforating psedoxanthoma elasticum.
There is no efficient therapy, treatment being aimed at controlling the symptoms. Various treatments which have been tried include topical steroids under occlusion, intralesional triamcinolone, tazarotene, tacalcitol, keratolytics and emollients. Other treatment modalities include antihistaminics, acitretin, cyclosporine, methotrexate, allopurinol, isotretinoin, narrow-band ultraviolet B, cryotherapy, diaphenyl sulfone, tranilast and compound glycyrrhizin tablets, with different degrees of improvements. Antimicrobials like Rifampicin, Clindamycin and Doxycycline have been used, with improvement which proves that presence of infectious agents may contribute to the development of ARPC.[7] Recognition and control of associated disease may help to treat ARPC.[2,3,4,5,7]
Though multiple therapeutic modalities are available, the curative effect is not satisfactory with only symptomatic improvement rather than complete cure, also duration of treatment is long, ranging from 2 weeks to 4 months.[3]
Financial support and sponsorship
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Conflicts of interest
There are no conflicts of interest.
REFERENCES
1. Shah H, Tiwary AK, Kumar P. Transepidermal elimination: Historical evolution, pathogenesis and nosology Indian J Dermatol Venereol Leprol. 2018;84:753–7
2. Fei C, Wang Y, Gong Y, Xu H, Yu Q, Shi Y. Acquired reactive perforating collagenosis: A report of a typical case Medicine. 2016;95:30
3. Xinyue Z, Yan Y, Shiying S. Acquired reactive perforating collagenosis: A case report and review of the literature Medicine. 2020;99:e20391
4. Kreuter A, Gambichler T. Acquired reactive perforating collagenosis CMAJ. 2010;182:E184
5. Zhang H, Jian-Min, Chang JM. Reactive perforating collagenosis Int J Dermatol Venereol. 2019;2:62–4
6. Molin S, Ruzicka TGriffiths C, Barker J, Bleiker T, Chalmers R, Creamer D. The skin and disorders of kidney and urinary track Rooks Textbook of Dermatology.. 20162nd ed. UK Wiley Blackwell:153
7. Escribano-Stablé JC, Doménech C, Matarredona J, Pascual JC, Jaen A, Vicente J. Tacalcitol in the treatment of acquired perforating collagenosis Case Rep Dermatol. 2014;6:69–73
