Quiz 63: What is your diagnosis?

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Diagnosis: Quiz 63

Quiz 63

Answer:  Drug eruption, urticarial

Criteria for diagnosis clinically:  Annular, arcuate, and polycyclic lesions with a pink raised border, the inner margin of which is accentuated by a thin violaceous band, and with a dusky center, are those of a drug eruption of one kind, to wit, the urticarial.

Differential diagnosis clinically: Almost certainly the lesion is benign, it being symmetrical, sharply circumscribed, and throughout most of it a single shade of dark brown, but should there be any concern whatsoever about the possibility of its being melanoma, removal should be in toto. Having done that, it becomes possible to identify the type of nevus, in this case, it being Zitelli's.

Criteria for diagnosis histopathologically:  The findings of a sparse superficial perivascular and interstitial infiltrate with lymphocytes present mostly around venules and eosinophils and neutrophils in the interstitium in conjunction with edema in loci of the papillary dermis, a few extravasated erythrocytes in the upper part of the dermis, and an occasional lymphocyte in an epidermis that sports a rare necrotic keratocyte are in keeping with an urticarial drug eruption.

Differential diagnosis histopathologically This could be an urticarial allergic eruption induced by an agent other than a drug, e.g., an infestation.

Clinicopathologic correlation The lesions are elevated at their periphery by virtue of a combination of the infiltrate of inflammatory cells and edema of the papillary dermis; the violaceous cast is a consequence of some erythrocytes having been extravasated in the upper part of the dermis; the redness is the result of venules and capillaries, in vivohaving been filled with red blood cells; and the surface of the lesion is smooth because the stratum corneum is normal.

Options for therapy predicated on knowledge of histopathologic findings Once a diagnosis of drug eruption is suspected, a clinician must review the medications currently being taken by the patient and seek to identify the culprit. In this instance, the drug was found to be Avelox (clinolon), an antibiotic. Once the drug was interdicted the lesions disappeared slowly but surely.

1) The presentation clinical of the lesions in this patient is referred to conventionally by dermatologists as figurate erythema or gyrate erythema. The term figurate is descriptive of lesions whose contours have assumed a distinctly recognizable form, they usually being ones arcuate, annular, polycyclic, and at times serpiginous. Gyrate means coiled or winding around a central point, which is not applicable to skin lesions of any form. Moreover, the designation figurate erythema is not a diagnosis with specificity. Many different diseases of the skin, most of them inflammatory, can be associated with appearances geometric considered to be figurate, among them being erythema annular centrifigum, erythema multiforme, granuloma annulare, subacute cutaneous lupus erythematosus, and at times psoriasis. Among neoplastic diseases, mycosis fungoides is known to present itself with figurate lesions. In short, the term figurate erythema is an encumbrance to coming to a diagnosis with precision because it is an evasion from a diagnosis and, therefore, should be eschewed. Rather than invoke that name distracting, a clinician is advised to proceed directly to a diagnosis with exactness, such as urticarial drug eruption.

2) Although erythema multiforme is in the differential diagnosis clinically, none of the lesions in this patient truly are rings arranged concentrically ("target lesions") and none consist of a purpuric punctum in the center of a red papule ("iris lesion"). In brief, in the absence of those aspects stereotypical of erythema multiforme, that diagnosis cannot be made clinically with surety. In fact, this patient does not have erythema multiforme.

3) The best diagnosis for this patient on grounds clinical and histopathologic is a drug eruption of one kind. Even though that diagnosis cannot be made with certainty, it is the most reasonable not only because the changes are consonant with an urticarial drug eruption, but they do not conform precisely to those of any other inflammatory disease of the skin.

4) The diagnosis "drug eruption" is as imprecise as "figurate erythema." There are many different types of "drug eruptions," i.e., conditions brought into being by a drug administered systemically, e.g., erythema multiforme, erythema nodosum, leukocytoclastic vasculitis, lupus erythematosus-like, and lichenoid, to mention but a few. The only drug eruption that can be diagnosed with confidence histopathologically is "fixed drug eruption," the findings in it being utterly specific.

5) When a histopathologist issues a diagnosis of "drug eruption," it always is advisable to addend mention of the precise type of drug eruption. In this instance, the changes of a superficial perivascular interstitial infiltrate of lymphocytes mostly around venules and a superficial interstitial infiltrate of eosinophils and neutrophils are representative of an allergic (hypersensitivity) reaction, the offending allergen here being a drug.

6) The lesions in this patient are urticarial (hive-like), clinically and histopathologically, because they simulate those of authentic urticaria, namely, pink edematous papules/plaques clinically, and they consist of perivascular and interstitial infiltrates made up of lymphocytes, eosinophils, and neutrophils. In true urticaria, however, the lesions clinical hardly ever are associated with purpura and the sparse infiltrate of inflammatory cells involves the reticular dermis; the papillary dermis, the dermoepidermal junction, and the epidermis are spared. Furthermore, lesions of urticaria wane within hours, whereas lesions urticarial, such as the ones pictured here, persist for days at least. Examples of lesions urticarial, i.e., not true urticaria but resembling it clinically, are responses hive-like to insect bites, hive-like lesions of dermatitis herpetiformis, and hive-like lesions of bullous pemphigoid. Biopsy of hive-like lesions of those three diseases produces a specimen from which sections cut show changes specific for each of them at a stage urticarial clinically.

7) Urticaria may be called forth by factors allergic or non-allergic, the former being manifested usually as what has been called "acute urticaria," induced by ingestants, inhalants, injectants, and infestations, whereas the latter is expressed as what has been designated "chronic urticaria," the cause of which hardly ever is determined, but the mechanism of which is not thought to be immunologic. Agents physical, among them cold, pressure, and heat, are among those responsible for non-allergic urticaria.

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