Quiz 51: What is your diagnosis?

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Diagnosis: Quiz 51

Quiz 51

Answer: Lupus erythematosus, acute discoid

Criteria for diagnosis clinically: Widespread, bright red papules, many of which have become confluent to form plaques ill-defined, are in keeping with lupus erythematosus.

Differential diagnosis clinically: This could be a drug eruption or even a photoallergic dermatitis. Biopsy is essential to coming to a diagnosis with specificity.

Criteria for diagnosis histopathologically: In addition to a sparse lymphoplasmacytic infiltrate around widely dilated venules of the superficial plexus, there are prominently telangiectatic capillaries in loci of the papillary dermis, a smudged appearance of the dermoepidermal junction (especially well visualizable on the right side of this section of tissue), a hint of vacuolar alteration in loci, muting of the undulate pattern between rete ridges and dermal papillae, occasional necrotic keratocytes in the spinous zone, focal hypergranulosis, and compact orthokeratosis-all of those changes, in toto, being in synchrony with lupus erythematosus.

Differential diagnosis histopathologically: Changes identical to these may be encountered in dermatomyositis.

Clinicopathologic correlation: The slightly raised papules are formed by the infiltrates of inflammatory cells, the bright redness is a consequence of erythrocytes having been present in vivo in the strikingly dilated venules and capillaries in the uppermost part of the dermis, and the orthokeratosis is too little to be noticeable clinically as scale.

Options for therapy predicated on knowledge of histopathologic findings: This being an inflammatory process believed to be mediated by mechanisms immunologic, it would be expected to respond to a high dose of corticosteroid administered systemically, which, in fact, was the case here.

1) Although a diagnosis of lupus erythematosus cannot be made on the basis of features clinical alone, that diagnosis surely is one of two considerations histopathologic, the other being dermatomyositis. In some instances, the changes histopathologic of dermatomyositis are indistinguishable from those of lupus erythematosus, and that is the situation here. The attribute in this section of tissue crucial for identification of the lesion as being that of either lupus erythematosus or dermatomyositis is the "smudged" appearance of the dermoepidermal junction in a locus seen best on the right. That, in conjunction with the infiltrate of lymphocytes mostly, the telangiectases, and the vacuolar alteration makes this either lupus erythematosus or dermatomyositis.

2) This particular expression of lupus erythematosus qualifies as "acute discoid" because the lesions are bright red clinically, and in addition to perivascular lymphoplasmacytic infiltrates, the dermoepidermal interface is but affected slightly. Surely this is not a fully formed lesion of discoid lupus erythematosus because of the absence of a moderately dense superficial and deep perivascular infiltrate of lymphocytes or even a suggestion of a thickened basement membrane beneath a thinned epidermis. The patient was not taking a drug known to induce lesions cutaneous of lupus erythematosus. We have chosen to designate this "subacute discoid lupus erythematosus" for want of a better term.

3) We conceive of this particular expression of lupus erythematosus as "acute discoid," but that judgment is somewhat arbitrary because the changes do not conform precisely to criteria established for categorization of cutaneous lesions of lupus erythematosus. It was that realization of lack of constancy between the manner in which a disease manifests itself and the preconceived idea of a pathologist about how the disease should present itself that prompted Charles Dunlap, the Chair for many years of the Department of Pathology at Tulane, to remind often that, "The diseases don't read the textbooks."

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