Quiz 53: What is your diagnosis?

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Diagnosis: Quiz 53

Quiz 53

Answer: Lupus erythematosus, subacute cutaneous

Criteria for diagnosis clinically: Dusky red papules and plaques, many of them having become confluent to form lesions polycyclic, are those of subacute cutaneous lupus erythematosus.

Differential diagnosis clinically: Because these lesions are present mostly in photodistribution, there really is no differential diagnosis.

Criteria for diagnosis histopathologically: The constellation of a sparse superficial and deep perivascular infiltrate of lymphocytes, an increase in mucin in loci of the reticular dermis, striking telangiectases in the upper half of the reticular dermis, a focus of lichenoid infiltration of lymphocytes, a sprinkling of lymphocytes in association with vacuolar alteration at the dermoepidermal junction, and an appearance of smudging of that junction situated beneath a strikingly thinned epidermis whose cornified layer is normal computes to a diagnosis of lupus erythematosus.

Differential diagnosis histopathologically: This could be dermatomyositis because, at times, the two conditions are indistinguishable from one another as assessed by microscopy conventional. The locus of lichenoid infiltration of lymphocytes militates somewhat against dermatomyositis.

Clinicopathologic correlatio: The lesions are elevated by dint of the infiltrates of inflammatory cells and the deposits of mucin, they are dusky red because venules in the upper half of the reticular dermis are expanded widely and, in vivo, were crammed with erythrocytes, and the surface of the lesion is smooth because the cornified layer is mostly normal.

Options for therapy predicated on knowledge of histopathologic findings: Because there are so many lesions, this patient would profit from systemic administration of chloroquine, that chemical being found empirically to be effective in various active cutaneous expressions of lupus erythematosus.

1) The features clinical are typical of that manifestation of lupus erythematosus known as subacute cutaneous. That that condition is an equivalent of acute discoid lupus erythematosus can be inferred from the findings histopathologic, they being indistinguishable from those of that particular expression clinical of lupus erythematosus.

2) Although one presentation of lupus erythematosus is identical histopathologically to one manifestation of dermatomyositis, there are times when lupus erythematosus is distinguished easily from dermatomyositis. For example, in a fully-established lesion of discoid lupus erythematosus where dense perivascular infiltrates of lymphocytes are present throughout the reticular dermis and in lobules in the upper part of the subcutaneous fat in conjunction with a thickened basement membrane that resides just beneath a thinned epidermis, the possibility of dermatomyositis is nil. Even in the photomicrograph shown here, the diagnosis is more likely lupus erythematosus than dermatomyositis because on the right side of the photomicrograph "shot" at scanning power magnification the infiltrate of lymphocytes is patchy lichenoid, a finding much more common in lupus erythematosus than in dermatomyositis.

3) Although the epidermis in this section of tissue of lupus erythematosus is very thin, it can become even thinner in time, for example, in a later stage of subacute cutaneous lupus erythematosus and in chronic discoid lupus erythematosus. A paper thin epidermis is encountered in but few conditions in the skin, among them being lupus erythematosus (including Degos' disease), dermatomyositis, and in the atrophic center of a lesion of those types of porokeratosis that are somewhat annular clinically.

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