Case 1 History
A 55-year-old female presents with scaly white plaques involving her vulva.
Microscopic Findings
Histopathology reveals epidermal atrophy with blunting of rete and overlying orthohyperkeratosis ( Fig. 10.1 ). The basilar epidermis shows patchy vacuolar degeneration with nearby lymphocytes. There is a broad area of the expanded papillary dermis showing pale, edematous, and homogenized collagen. Beneath this, there is a variably dense bandlike inflammatory infiltrate.
Diagnosis
Lichen Sclerosus
Clinical Presentation
Lichen sclerosus most commonly affects adult females in the genital area, although extragenital and pediatric presentations may also occur.
Histopathology
The histopathologic findings of lichen sclerosus vary depending on the chronicity of the area of involvement. Early involvement shows a lichenoid inflammatory infiltrate with vacuolar alteration and necrosis of basilar keratinocytes. Fibrosis may be subtle in early disease. As the process evolves, the epidermis becomes atrophic with overlying orthokeratotic hyperkeratosis. Vacuolar degeneration of basal keratinocytes persists, and there are homogenization and hyalinization (sclerosis) and papillary dermal collagen jointly with edema. Loss of elastic fibrils may occur. The lichenoid infiltrate is pushed down beneath this altered collagen and appears as a vaguely bandlike infiltrate beneath the altered papillary dermal collagen and consists of lymphocytes, histiocytes, and eosinophils.
Differential Diagnosis
The differential diagnosis includes morphea, radiation dermatitis, hypertrophic scar, and keloid ( Table 10.1 ).
| Lichen Sclerosus | Morphea or Scleroderma | Radiation Dermatitis | Scar or Keloid | |
|---|---|---|---|---|
| Epidermis | Atrophic with orthokeratotic hyperkeratosis | Normal or atrophic | Often atrophic with orthokeratotic hyperkeratosis | Atrophic and effaced |
| Classic features | Lichenoid infiltrate early; homogenized papillary dermal sclerosis in fully developed disease | Interstitial dermatitis with plasma cells early; diffuse reticular dermal sclerosis in fully developed disease | Hyalinized sclerosis with telangiectasia and pleomorphic stellate fibroblasts | Diffuse fibrosis with perpendicular vessels; admixed keloidal collagen |
Morphea
Clinical Presentation
Morphea presents as a localized thickened, pale sclerotic plaque, most commonly on the trunk. Widespread involvement may also occur.
Histopathology
The histopathologic findings associated with morphea ( Fig. 10.2 ) vary with chronicity. Early morphea shows a lymphoplasmacytic inflammatory infiltrate in the deep dermis at the junction with the subcutis, interstitially in the deeper dermis, and around adnexa. Associated alteration of collagen may be subtle at this phase of development. As the disease progresses, later involvement shows thickened sclerotic dermal collagen with minimal or scattered inflammation. Biopsies of fully developed morphea appear squared in profile because of thickened dermal collagen. A biopsy of normal skin appears tapered in profile; by contrast, a biopsy of morphea maintains rectangular morphology because of sclerotic collagen. At high magnification, collagen bundles appear coarsened, and the spaces between them appear reduced. There may be parallelism of elastic fibrils.
Adnexa in late involvement often appear atrophic or compressed, and periadnexal adipocytes may be reduced. There may also be atrophy or muting of the epidermis. Superficial variants of morphea show similar sclerosis limited to the upper half of the reticular dermis. Interestingly, some patients show features of lichen sclerosus superficially with morpheic involvement of the deeper dermis. This composite involvement has been informally referred to as lichen sclerosus et morphea .
Radiation Dermatitis
Clinical Presentation
Chronic radiation dermatitis presents as scaly whitish thickened plaques at sites of prior irradiation. In some cases (see later discussion), the clinical history of radiation is critical to establishing the correct diagnosis.
Histopathology
Chronic radiation dermatitis often shows epidermal atrophy with overlying orthohyperkeratosis, similar to lichen sclerosus ( Fig. 10.3 ). There may be nuclear enlargement and variability of scattered keratinocytes. The dermis shows a constellation of features, including dense hyalinized sclerotic collagen, similar to morphea, as well as telangiectatic vessels, fragmented elastic fibers, and scattered pleomorphic fibrocytes. These latter features typically facilitate the distinction from lichen sclerosus, although overlap can be found.
Scar
Clinical Presentation
Scars develop at sites of prior trauma or physical effect and manifest as areas of whitish or pale pink thickened skin.
Histopathology
A typical scar shows flattening of the epidermis with effacement of rete ( Fig. 10.4 ). In the subjacent dermis, there is collagen and fibroblasts oriented parallel to the epidermis and thin vessels oriented perpendicularly to this. Early scars may exhibit admixed mucin. Long-standing scars may include coarse collagen bundles.
Keloid
Clinical Presentation
Keloidal scars represent an exuberant variant of hypertrophic scarring that results in bulbous nodules. By definition,a keloid represents a wound-healing reaction that exceeds the size of the injury or trigger that elicited it.
Histopathology
Keloids show nodular scarring fibrosis with increased fibroblasts and mucin as well as central characteristic markedly thickened brightly eosinophilic collagen bundles ( Fig. 10.5 ). In circular fashion, these bright collagen bundles are referred to as keloidal collagen .
Case 2 History
An 85-year-old male presents with bilateral purpuric macules around the eyelids.
Microscopic Findings
Sections show deposits of dense amorphous homogenous pale amphophilic material in the dermis ( Fig. 10.6 ). Some of these deposits contain cracks. There are associated plasma cells.
Diagnosis
Nodular Amyloidosis (Primary Systemic Amyloidosis)
Clinical Presentation
Primary systemic (nodular) amyloidosis commonly presents in patients with multiple myeloma or plasma cell dyscrasia as purpuric macules, which can be found involving skin of the eyelids (representing so-called pinch purpura ).
Histopathology
Histopathologic evaluation reveals diffuse deposition of pale eosinophilic or amphophilic amorphous material in the dermis, around adnexa, and around blood vessels. There may be extravasated red blood cells. Congo red staining highlights this material and further demonstrates “apple-green” birefringence under polarized light.
Differential Diagnosis
The main differential diagnostic considerations include keratinocyte-derived amyloidosis (combining both lichen amyloidosus and macular amyloidosis) ( Table 10.2 ).
| Primary Amyloidosis | Keratin-Derived Amyloidosis | |
|---|---|---|
| Epidermis | Atrophic or normal | Irregular hyperplasia with hyperkeratosis, sometimes |
| Dermis | Deposition of pale amorphous material in the reticular dermis, often with associated plasma cells | Pale eosinophilic deposits in the papillary dermis with a variable lymphohistiocytic infiltrate |
Keratinocyte-Derived Amyloidosis
Clinical Presentation
Lichen amyloidosus presents as lichenified pebbly papules that coalesce into plaques on the shins and lower extremities in the context of chronic pruritus and lichenification. Macular amyloidosis presents most commonly on the back as areas of brown discoloration with a rippled pattern and is associated with chronic pruritus. A third, less common subtype, amyloidosis cutis dyschromica, is histopathologically similar or identical yet presents clinically in a widespread fashion.
Histopathology
Keratinocyte-derived amyloidosis may show epidermal hyperplasia with overlying hypergranulosis and hyperkeratosis ( Fig. 10.7 ). In lichen amyloidosus, epidermal hyperplasia is consistently present; by contrast, macular amyloidosis is often macular with an absence of associated acanthosis. There is a slight superficial lymphohistiocytic infiltrate in some instances. The diagnosis rests on the identification of distinctive pale eosinophilic globules in the papillary dermis (within dermal papillae). There may be associated melanophages.
Case 3 History
A 55-year-old female presents with bilateral doughy swelling of her bilateral lower extremities. Physical examination is notable for bilateral protruding eyes and goiter.
Microscopic Findings
Histopathologic sections reveal diffuse deposition of interstitial mucin amid the reticular dermal collagen bundles. Fibroblasts are not increased, and there is sparing of the papillary dermis ( Fig. 10.8 ).
Diagnosis
Pretibial Myxedema
Clinical Presentation
Pretibial myxedema typically develops in the setting of Graves disease and presents as a bilateral thickened swelling of the bilateral lower extremities with a doughy consistency.
Histopathology
Histopathologic analysis reveals deposition of bluish interstitial mucin throughout the reticular dermis. The papillary dermis is typically spared, and fibroblast density is typically normal. The mucin can be highlighted by Alcian blue or colloidal iron staining.
Differential Diagnosis
The differential includes lichen myxedematosus (scleromyxedema) and scleredema.
Lichen Myxedematosus (Papular Mucinosis or Scleromyxedema)
Clinical Presentation
Lichen myxedematosus (papular mucinosis) presents as papules on the face or neck as well as the hands and forearms in some cases ( Table 10.3 ). Some patients have an associated monoclonal gammopathy.
| Pretibial Myxedema | Lichen Myxedematosus | Scleredema | |
|---|---|---|---|
| Clinical association | Graves disease | Monoclonal gammopathy, often | Diabetes mellitus, often; monoclonal gammopathy, sometimes |
| Clinical distribution | Bilateral lower leg | Face and neck | Trunk |
| Histopathology | Prominent mucin deposition in the reticular dermis | Dermal mucin deposition with increased spindled cells | Thickened reticular dermis, often with deep mucin deposition |
| Interstitial cellularity | Normal or reduced | Increased | Normal or reduced |
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