Quiz 32: What is your diagnosis?

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Diagnosis: Quiz 32

Quiz 32

Answer:  Picker's ("nodule") plaque

Criteria for diagnosis clinically: An erosion with a peculiar shape associated with scale-crust and in the midst of a broad, ill-defined zone of lichenification is that of a picker's ("nodule") plaque.

Differential diagnosis clinically: Because this could be a carcinoma, biopsy is mandatory for coming to a diagnosis with precision.

Criteria for diagnosis histopathologically: The constellation of striking infundibular hyperplasia and less notable eccrine ductal hyperplasia affiliated with wedge-shaped hypergranulosis and compact orthokeratosis, in association with large scale-crusts made up of parakeratosis, serum, extravasated erythrocytes, and neutrophils, as well as coarse bundles of collagen arranged in vertical streaks in some dermal papillae widened decidedly by them, sum to a diagnosis of picker's ("nodule") plaque.

Differential diagnosis histopathologically: There is none.

Clinicopathologic correlation: The plaque came into being by dint mostly of infundibular and eccrine ductal hyperplasia; the pink hue is a consequence of dilated capillaries in dermal papillae, they, in vivo, having been stuffed with erythrocytes; the erosion seen clinically is explained by the erosion identifiable histopathologically; and the scale-crust apparent clinically is accounted for by the prominent scale-crust noticeable histopathologically.

Options for therapy predicated on knowledge of histopathologic findings: The plaque resulted from rubbing persistently and forcefully of this particular site for many months and possibly many years, and the erosion is a consequence of episodic scratching animatedly. That being so, the management requisite is education of the patient about the reasons for how the lesion came into being and encouragement to desist from rubbing and scratching, that being aided by helpful hints to achieving that desideratum, such as application of ice or non-fluorinated corticosteroid applied gently when itching becomes vexing. If cessation of external trauma commences, the skin, in time, will return to normal, that taking at least many months to attain.

1) The word "nodule" has been placed in quotation marks because although that designation is the one usually given to a lesion histopathologic such as this one, in fact it is not a nodule clinically, but a plaque. In fact, the lesion produced by rubbing could be termed "lichen simplex chronicus," but the findings histopathologic are most consonant with what conventionally is dubbed "picker's nodule." In actuality, nomenclature is not important here; what must be understood is that all of the changes pictured, clinical and histopathologic, are factitious, i.e., they were produced entirely by rubbing and scratching.

2) The evidences here of persistent rubbing are compact orthokeratosis of surface and of infundibular epidermis, wedge-shaped hypergranulosis of infundibula, and bulbous hyperplasia of infundibula and, to a lesser extent, eccrine ducts. The coarse bundles of collagen in vertical streaks in a widened papillary dermis also are a sign of rubbing relentlessly. The evidences of excoriation not only are the erosion and the scale-crust, but the presence of neutrophils in collections within some infundibula, they sometimes being a manifestation, too, of secondary infection by bacteria. In brief, all of the features and findings shown here are a consequence of rubbing arduous and scratching vigorous for years.

3) This is not a squamous-cell carcinoma because the proliferation of keratocytes is formed almost entirely of infundibular epidermal and eccrine ductal keratocytes. Moreover, at the periphery and base of those bulbous structures, nuclei are not crowded and arrayed in a jumble, neither are they large, pleomorphic, and heterochromatic. In short, the epithelial abnormality pictured here does not fulfill criteria for squamous-cell carcinoma, but does satisfy criteria for picker's ("nodule") plaque.

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