Morphea - Submitted on: Wednesday May, 03, 2000

Contributed by:Artur Zembowicz, MD PhD., N/A

Morphea (localized scleroderma) is a group of disorders of dermis and subcutaneous tissue clinically presenting as localized areas of dermal thickening and hardening related to sclerosis in deep dermis and subcutaneous tissue. Morphea is a self limited variant of scleroderma without systemic involvement such as in systemic sclerosis. Relationship between morphea and systemic sclerosis is unclear although both conditions share many similarities in gross (clinical) and microscopic appearance of the cutaneous lesions.

Definition: Morphea is a localized self-limiting variant of scleroderma characterized morphologically by deep dermal and subcutaneous collagen deposition and sclerosis.

Clinical Features: Morphea is the most common form of scleroderma. It has wide age distribution with predilection for children and young adults, with female predominance. Numerous clinical subsets of morphea are recognized. Classification of different variants is primarily based on size and pattern of lesion distribution. These include plaque-like form, linear (en coup de sabre), guttate, facial hemiatrophy, generalized and subcutaneous (morphea profunda) variants of morphea. Although clinical appearances of individual lesions are similar to those in systemic sclerosis, morphea is not associated with internal organ involvement. Progression of morphea to systemic sclerosis is extremely rare. Pathogenesis of morphea is unknown. Some studies suggest association with trauma or infection. Several cases of morphea profunda have been associated with Borrelia burgdorferi infection.

Histology: Figures (Click on an image for a larger view) Figure 1. Desmoplastic melanoma on low power exhibits intraepidermal melanocytic hyperplasia with hyperpigmentation overlying fibrotic dermis (area of close-up in Figure 2). Figure 2. Closeup in area of fibrotic dermis in Figure 1 shows epithelioid cells superficially with elongate hyperchromatic spindle cells below dermis. Figure 3. Note multinucleate cells, some of which appear pyknotic. Figure 4. In this dense fibrous matrix, highly irregularly shaped hyperchromatic cells are evident and are characteristic of desmoplastic melanoma cells. Figure 5. The classic features of lentigo maligna shown here include epidermal atrophy, single dispersed atypical melanocytes along the basilar of the epidermis and the external root sheath of the hair follicle. There is also solar elastosis and chronic i Figure 6. Neurotropism is evidenced by thickening of the stroma by nevoid cells. Note the multinucleate desmoplastic melanoma cells within the stroma in the subcutaneous fat. Figure 7. Desmoplastic melanoma cells react positively with antibodies directed against S-100 proteins. Histological features of morphea are very characteristic. However, it should be noted that distinction between morphea and systemic sclerosis on histological sections can not be made with high reliability. Low power appearance of biopsies of morphea show square biopsies, which differ from typical wedge-shaped biopsies of normal skin. Multinucleated cells and individual necrotic cells may be present (Figure 3). Mitotic figures are rare. Focal lymphocytic aggregates (nodules) are a constant and diagnostically helpful feature. Macrophages may be scattered throughout the lesion. The degree of cellularity and of collagen production varies greatly from case to case (Figure 4). Areas with myxoid or storiform appearance can be seen. Whenever an overlying radial growth phase melanoma is coexisting, it has the features of one of the common types of intraepidermal melanomas and contributes greatly to the recognition of the exact nature of the lesion underneath (Figure 5). Infiltration of the adventitia of blood vessels and/or the perineurium and endoneurium of local nerves is found in a significant percentage of cases and is considered to be helpful in the final diagnosis (Figure 6). In present day thinking, the hypothesis that desmoplasia is due to metaplasia of the melanocytes has supervened the previous belief that increase of collagen represents a host reaction to the neoplastic invasion. IMMUNOHISTOCHEMISTRY DM's neoplastic cells usually show immunoreactivity with S-100 protein (Figure 7) and NKI/C3. Nevertheless, negativity does not exclude the diagnosis when the clinical picture and/or histology are characteristic. HMB-45, NKI/beteb, and Leu-7 (CD57), and NSE usually do not stain DMs (with rare exceptional cases of usually focal reactivity in an epithelioid neoplastic subpopulation). CD68 has been demonstrated in a minority of cases. The reported SMA positivity has been shown to be related to myofibroblastic differentiation of a spindle cell component in some cases with S-100 and desmin immunonegativity.

Treatment: Wide excision of the primary lesion with clear margins and close follow-up are necessary. It is extremely important that the lesion be extirpated in the initial surgical excision. Recurrences are usually an ominous sign. However, recurrences must also be widely excised.

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