More than 200 patients with prurigo pigmentosa, a disease described first by Nagashima in 1971, have been reported on in Japan, but only 28 non-Japanese patients have come to notice as of today. In order to establish reliable, repeatable criteria for diagnosis of the disease, we studied 25 patients with prurigo pigmentosa and reviewed the literature pertaining to it as recorded in another 182 patients.Clinically, prurigo pigmentosa presents itself as pruritic urticarial papules, papulovesicles, and vesicles arranged in reticular pattern and distributed symmetrically on the back, neck, and chest. Lesions involute in a matter of days, leaving behind netlike pigmentation. Exacerbations and recurrences are the rule. Histopathologically, prurigo pigmentosa begins with a superficial perivascular infiltrate of neutrophils. Shortly thereafter, neutrophils are scattered in dermal papillae and then sweep rapidly through an epidermis in which spongiosis, ballooning, and necrotic keratocytes are accompaniments. En route, abscesses may form in the surface epithelium. Very soon, eosinophils and lymphocytes come to predominate over neutrophils in a dermal infiltrate that assumes a patchy lichenoid pattern. Intraepidermal vesiculation follows on spongiosis and ballooning and, sometimes, subepidermal vesiculation on vacuolar alteration at the dermo-epidermal junction. As the epidermis becomes hyperplastic, parakeratotic, and slightly hyperpigmented, melanophages begin to appear in the dermis. Studies by immunofluorescence are negative invariably. Dapsone or minocyclin are effective treatments; both of those agents inhibit migration and/or function of neutrophils. The cause and pathogenesis have yet to be determined. Prurigo pigmentosa is unique among inflammatory diseases of the skin and the singularity of it is manifest both clinically and histopathologically.

Histopathologistics need to identify with confidence subtle signs of infundibular, follicular and sebaceous differentiation because these features are dependable criteria to differentiate DTE from MBCC. Immunohistochemistry for androgen receptors and CK20 is helpful, but interpretation is difficult in some DTEs when few cells are immunopositive for these markers.

It has been a subject of controversy whether keratosis lichenoides chronica (KLC) is a distinctive inflammatory disease of the skin or whether it represents a manifestation of another well-known disease, such as lichen planus, lupus erythematosus, or lichen simplex chronicus. In search of clear criteria for diagnosis of KLC the entire literature pertinent to the subject was studied and findings clinical and histopathologic as they were telegraphed in them were compared with a patient of my own experience. Review of the literature reveals more than 60 patients in whom the diagnosis of KLC was made. Three categories emerge based on whether the findings presented in a particular article (1) do not permit any diagnosis to be rendered; (2) do allow a diagnosis specific to be made, such as of lichen simplex, lichen planus, or lupus erythematosus; or (3) do not correspond to any disease well defined, such as lichen simplex, lichen planus, lupus erythematosus, but seem to show attributes morphologic, clinically and histopathologically, that are repeatable. Patients diagnosed as having KLC obviously represent a potpourri of different diseases, the most common of them being lichen simplex chronicus, lichen planus, and lupus erythematosus. Fewer than 25 patients reported on, however, presented themselves with lesions very similar to one another clinically, namely, an eruption that involved the face in a manner reminiscent of seborrheic dermatitis and with tiny papules on the trunk and extremities, which assumed linear and reticulate shapes by way of confluence of lesions. Individual papules were infundibulocentric and acrosyringocentric. Findings histopathologic were those of a lichenoid interface dermatitis affiliated with numerous necrotic keratocytes and covered by parakeratosis housing neutrophils in staggered fashion. These patients seem to have an authentic and distinctive condition that is exceedingly rare. In conclusion, the diagnosis of KLC should be made only for patients who present themselves with features clinical and findings histopathologic that resemble closely those of what is summarized in this article under category 3.

Prurigo pigmentosa is a distinctive inflammatory disease first described by the Japanese dermatologist Masaji Nagashima in 1971. It is typified by recurrent, pruritic erythematous macules, papules and papulovesicles that resolve leaving behind netlike pigmentation. The disease is rarely diagnosed outside Japan, because clinicians outside Japan are not well conversant with the criteria for its diagnosis. Only one patient from India has been published previously under the diagnosis of prurigo pigmentosa, a hint that the disease may be under-recognized in India. We present an account of our observations in patients diagnosed with prurigo pigmentosa who were of five different nationalities, namely, Japanese, German, Indonesian, Turkish and Iranian. With this article we seek to increase awareness for the condition among dermatologists in India and we provide criteria for its diagnosis, both clinically and histopathologically.

Forty per cent of all patients with IVL have skin lesions, these being red, sometimes painful plaques located typically on the lower extremities, accompanied by oedema. A clinician risks misinterpreting these changes as thrombophlebitis, erythema nodosum or erysipelas. Neither clinical course nor differentiation of the lymphoma can be predicted from the morphology of skin lesions, but involvement of other organs at the time of diagnosis indicates a poor prognosis.

CL seems often to be misdiagnosed clinically in countries where it is not endemic. Histopathologically, CL may be misinterpreted as sarcoidosis, foreign body granuloma, lupoid rosacea and granuloma annulare, especially when Leishmania is not seen microscopically. We suggest that in Northern Europe, PCR for Leishmania-specific DNA should be performed routinely in any granulomatous dermatitis presenting as a single or few nodules on the extremities or face, even when a diagnosis of CL was not considered by the referring clinician.

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B-cell and T-cell pseudoclones are not uncommonly encountered in moderately dense pseudolymphomatous infiltrates (23% and 13%, respectively). B-cell clonality is seen occasionally in pseudolymphomatous infiltrates (13%), especially when they are sparse in B lymphocytes. Therefore, rearrangement studies cannot be interpreted without correlation with morphological patterns and immunophenotyping of infiltrates and they need to be confirmed by duplicate or triplicate tests in order to prevent overinterpretation.