Crutchfield Dermatology Case-of-the-month header image

Case of the Month

A 33-year-old man presents with this scaling plaque on his shins and knees that appeared 3 years ago and have progressively expanded and intensified. They are extremely pruritic. The rest of his body is normal except some flaking and itching in and behind his ears.

leg with psoriasis before
leg after psoriasis treatment

What's Your Diagnosis?

Diagnosis: Psoriasis

When I gave him the diagnosis he told me “My grandfather had psoriasis!”


In this particular case I treated him Psorent solution (, CutiCort Spray (0.05% clobetasol in ethanol, isopropyl palmitate, isopropyl myristate and black raspberry seed oil) and Aquaphor spray. I had him stack these, in that order on top of one and other, waiting 30 seconds between applications, for 4 week I combined this with narrow-band UVB, 3x/week. The photos were taken 5 weeks apart. For a complete discussion on psoriasis, click here.

With Histopathologic Correlation


Psoriasis is an inflammatory disease of genetic nature that begins with red macules that quickly become non-scaly papules that, in turn, become scaly papules and plaques. If the process becomes widespread, an erythroderma results, and if it is accelerated, pustules form. The scaly discrete lesions favor extensor surfaces, especially elbows and knees, but any site may be affected, including nail units and, uncommonly, mucous membranes. Approximately 5 percent of patients with psoriasis develop an arthritis that, although it bears similarities to rheumatoid arthritis, seems to be different from it.

COURSE The chronologic sequence of lesions of psoriasis depends on the specific type of lesion. For example, eruptive (guttate) papules of psoriasis may wane and disappear in a matter of weeks, or they may wax to become plaques of psoriasis. Plaques of psoriasis tend to persist and may be confined to sites such as elbows and knees. If plaques are widespread, they may enlarge slowly, become confluent, and eventuate in erythroderma. Remarkably thickened plaques of psoriasis on the scalp, a kind of severe psoriasis totalis known colloquially as tinea amiantacea, tend to persist for decades. The same is true for psoriasis that affects palms and soles. In time, lesions on those latter sites often become fissured.

Pustules that erupt on psoriatic palms or soles come and go in an unpredictable fashion. Widespread pustules, a condition known as pustular psoriasis of von Zumbusch, erupt in a shower over the entire integument and, in the course of days or weeks, some pustules heal with crusts at the very same time that new pustules blossom. The course of widespread pustular psoriasis also cannot be predicted; for reasons still inexplicable, the process usually ceases after a matter of weeks, only to return with equal force when least expected.

INTEGRATING: UNIFYING CONCEPT All manifestations of psoriasis, are diagnosable, with surety, clinically and histopathologically. All of those expressions have in common sparse superficial perivascular, and interstitial infiltrates of lymphocytes, dilated tortuous capillaries in dermal papillae, and some degree of epidermal hyperplasia. They are usually accompanied by parakeratosis. Guttate lesions of psoriasis show edema of the papillary dermis, neutrophils within the epidermis in pustules that are given different names according to a different organization of neutrophils (e.g., Munro's microabscesses and spongiform pustules of Kogoj) and different sites (e.g., subcorneal and intracorneal pustules), and mounds of parakeratosis that sport neutrophils at their summits and that are staggered throughout the thickened cornified layer. Fully-developed lesions of psoriasis show psoriasiform hyperplasia with thin rete ridges of equal length that alternate with thin dermal papillae. Pallor usually is present in the upper part of the viable epidermis, the granular zone is nearly absent, except at sites of acrosyringia and acrotrichia, and confluent parakeratosis is laced with neutrophils. Asbestos-like psoriasis on a scalp is typified by all of the changes seen in fully-developed lesions of psoriasis but, in addition, is accompanied by a tremendously thickened parakeratotic layer. Pustular psoriasis is merely an acceleration and exaggeration of the psoriatic process in which neutrophils in large numbers race from capillaries in the dermal papillae toward the cornified layer and, en route, form abscesses within the epidermis known by the eponyms previously mentioned. Psoriatic erythroderma exhibits changes of fully-developed psoriasis in which there is only scant parakeratosis because scales are being shed constantly. In sum, all of the manifestations of psoriasis represent variations on a single pathologic, genetically-conditioned process that seems to be precipitated by different factors, e.g., streptococcal infection, physical trauma, or emotional stress. When that process involves the oral cavity, it is called "geographic tongue." When pustular psoriasis is situated on acral parts, especially on the thumb or fingers, it has gone by names such as acrodermatitis continua of hallopeau, dermatitis repens of Crocker, and pustular bacterid of Andrews. When pustular psoriasis occurs in someone who is pregnant, the name impetigo herpetiformis has been applied to it. When pustular psoriasis occurs in a patient with Reiter's syndrome, the designation keratoderma blenorrhagicum has been given to it. When pustules of psoriasis are arranged in arcuate, annular, serpiginous, and other figurate patterns, the condition has been called subcorneal pustular dermatosis of Sneddon and Wilkinson. Psoriasis of nail units in the form of pits on nail plates, onycholysis, and sublingual hyperkeratosis are all manifestations of the psoriatic process. That psoriasis is truly a systemic disease and can be realized by virtue of involvement by the process not only of the skin and nails, but of mucous membranes, gastrointestinal tract, and joints in the form of arthritis that may be mutilating.

THERAPY (general) For localized plaques, topical treatment with corticosteroids, anthralin, retinoids, vitamin D3 derivatives, and so-called keratolytics (salicylic acid) is recommended. For widespread papules and plaques, phototherapy, including PUVA, UV-B, and bath-PUVA therapy, as well as the Goeckerman regimen (tar plus UV-B), are advisable.

For nearly universal psoriasis, psoriatic erythroderma, and pustular psoriasis (von Zumbusch), oral retinoids, cyclosporin, or methotrexate in low dose are the treatments of choice. For psoriatic arthritis, methotrexate or cyclosporin is the best treatment. For psoriatic nails, injection of posterior nail folds with corticosteroids, albeit painful, is effective. For tinea amiantacea, solutions of salicylic acid plus corticosteroids are palliative.

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Charles Crutchfield III M.D. Eagan Dermatologist

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