Quiz 57: What is your diagnosis?

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Diagnosis: Quiz 57

Quiz 57

Answer: Urticaria

Criteria for diagnosis clinically: Smooth-surfaced, pink papules, some of them discrete, but others having become confluent to assume plaques of shapes peculiar, are those of urticaria.

Differential diagnosis clinically: Although urticarial lesions, such as those induced by "bites" of insects, could be considered here, the best diagnosis is authentic urticaria.

Criteria for diagnosis histopathologically: A rather sparse, superficial and mid-dermal, perivascular and interstitial infiltrate made up near entirely of neutrophils is that of urtica.

Differential diagnosis histopathologically: There is none.

Clinicopathologic correlation: The lesion is elevated somewhat by virtue of the infiltrate of neutrophils, but mostly by edema in the reticular dermis, which cannot be recognized for what it is in sections of tissue prepared from biopsy specimens processed routinely. The reddish cast is a consequence of wide dilation of venules of the superficial plexus, they, in vivo, having been stuffed with erythrocytes. The surface is smooth because the stratum corneum is normal.

Options for therapy predicated on knowledge of histopathologic findings: The causes of urticaria are numerous, among them inhalants, ingestants, injectants, and infestations, but, in many instances, no cause can be established. When a cause is known, such as an allergic reaction to shellfish, there need only be cessation and avoidance of the precipitating offender and, depending on the severity of the process, administration of an antihistaminic, a corticosteroid, or epinephrine. When lesions of urtica come and go for years in the absence of a identifiable specific cause, even though nonsteroidal compounds administered parenterally are a near uniform recommendation, they are not efficacious routinely.

1) "Urtica" is Latin for a nettle, that is, a weed that has stinging hairs. Synonyms for urtica are wheal or hive. Urticaria refers to a condition typified by (-aria) hives (urtic-)

2) Urtica is a pattern morphologic of skin analogous to suppurative infundibulitis, leukocytoclastic vasculitis, Sweet's syndrome, etc. Diagnosis of it is straightforward, predicated on features clinical and findings histopathologic, but on the basis of observations morphologic alone, hardly ever can the cause of urticaria be determined-and there are many of them. Neither is it possible by observation gross or by examination microscopic to decide whether the cause of urticaria is allergic or non-allergic.

3) Edema present in quantity in the papillary dermis, such as occurs commonly in severe allergic contact dermatitis, polymorphous light eruption, a response to the assault of an arthropod and adjacent to suppurative infundibulitis as shown in Quiz 776, is identifiable readily at scanning power magnification by dint of marked pallor of that widened uppermost part of the dermis. In contrast, edema in the reticular dermis, which is the site of it in urtica, cannot be discerned at all because the biopsy specimen had been immersed for hours or days in fluid, e.g., formalin, which contributed inevitably to formation of spaces artefactual between bundles of collagen in the reticular dermis. The amount of edema in the reticular dermis in urtica is negligible compared to the quantity of fluid of the fixative lodged in the interstitium there.

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