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Psoriasis is a common autoimmune dermatosis representing an interplay between certain genetic predisposing factors along with clonally restricted Th1 T cells responding to epidermal keratinocyte derived antigen. A unique IL17/IL23 cytokine-rich milieu is pathogenetically significant and conducive to its salient histomorphologic features, such as epidermal hyperplasia and intraepidermal influx of neutrophils. The classic cutaneous manifestation is that of plaque psoriasis also referred to as psoriasis vulgaris with characteristic well-circumscribed erythematous plaques covered by silvery scales. Follicular psoriasis is an uncommon variant manifesting as a scaly folliculocentric hyperkeratotic eruption of the trunk and extremities, irrespective of the presence or absence of conventional lesions of psoriasis vulgaris. In this study we present 5 cases of follicular psoriasis, review the literature, and provide a proposal regarding relevant pathologic findings and potential pathogenetic mechanisms. The incidence of follicular psoriasis is unknown, emphasizing its rarity given the overall incidence of conventional psoriasis in the general population. Owing to the lack of awareness, this clinical presentation is often mistaken for other follicular dermatoses, including bacterial folliculitis, pityriasis rubra pilaris, keratosis pilaris, or follicular eczema.

Lymphomatoid drug reactions can mimic endogenous T and B cell lymphoproliferative diseases.We present a novel form of cutaneous drug reaction with features of pityriasis lichenoides (PL), a recognized form of T cell dyscrasia.Ten cases were studied where a cutaneous eruption exhibiting semblance to PL within a few weeks to months after starting a particular drug.The patient cohort comprised 7 females and 3 males with the mean age of 60 years. Widely distributederythematous cutaneous lesions were present in 6 cases whereas a more localized distribution was seen in three cases. The most frequently implicated drugsassociated with the eruption were antidepressants and statins. Histologic examination showed a morphologic picture identical to PL including marked epitheliotropism of mildly atypical lymphocytes, psoriasiform epidermal hyperplasia, dyskeratosis, hemorrhage, and a thick parakeratotic scale. Therewas a significant reduction in the expression of CD7 and CD62L amid the T cells. Regression of the eruption occurred in all cases excluding one.Thefindings conform the categorization of this process as a form of T-cell dyscrasia albeit one that is reversible, dependent on the drug withdrawal. The limitationof our study includes the retrospective design of the study.

Hydralazine-induced small vessel vasculitis is a rare entity with a limited number of cases reported in the dermatologic literature. A characteristic pattern of acral pseudoembolic vesiculopustules with necrosis and ulceration has been suggested along with involvement of the aerodigestive tract, indicating mucosal involvement is an important feature of this disease. We report the case of a patient with hydralazine-induced vasculitis who exemplified this characteristic presentation associated with severe involvement of the aerodigestive tract and gastrointestinal tract bleeding. In addition to the distinctive clinical presentation, the patient's workup revealed the characteristic antineutrophil cytoplasmic antibody (ANCA)-positive serologic profile. Increased recognition of the clinical and serological features of hydralazine-induced small vessel vasculitis may lead to earlier recognition of this disease and decreased time to discontinuation of hydralazine when appropriate. Drug withdrawal is the cornerstone of therapy, and depending on the severity of symptoms, additional immunosuppressive treatment such as corticosteroids may be necessary.

Lymphomatoid papulosis (LyP) and cutaneous anaplastic large cell lymphoma (ALCL) belong to the spectrum of cutaneous CD30+ lymphoproliferative disorders, an indolent form of T-cell lymphoproliferative disease. We reviewed 21 cases of CD30+ lymphoproliferative lesions expressing cytotoxic profile (CD8+). Seven cases of cutaneous ALCL, 2 cases of systemic ALCL involving the skin, and 12 cases of LyP. The cases of LyP were predominated by small lymphocytes exhibiting a prominent epidermotropic pattern consistent with either type B or type D LyP. Four cases showed co-expression of CD56. The ALCL cases included myxoid features, pseudoepitheliomatous change, and an intravascular component. In all cases that were primary in the skin an indolent clinical course was seen while one patient with systemic myxoid ALCL is in remission following systemic multiagent chemotherapy. The paucity of other neutrophils and eosinophils and concomitant granulomatous inflammation were distinctive features in cases of type B and type D LyP. CD30 and CD45 Ro positivity and a clinical course typical of LyP were useful differentiating features from an aggressive cytotoxic CD8+ T cell lymphoma. In all cases that were primary in the skin an indolent clinical course was observed. CD30 and CD45 Ro positivity and a clinical course typical of LyP were useful in preventing a misdiagnosis of an aggressive cytotoxic CD8+ T cell lymphoma.

Although the histologic characteristics of cryofibrinogenemia have been described in skin lesions, the literature is largely devoid of descriptions of this disorder in other organs. This series is the first to document the histopathologic manifestations of intrapulmonary, intramuscular, and renal cryofibrinogenemia. We describe the histopathologic manifestations of cryofibrinogenemia in 10 cases with manifestations in 4 organ systems: skin in 7 cases, skeletal muscle in 2, lung in 2, and kidney in 1. Irrespective of anatomic site, all lesions showed an occlusive thrombotic diathesis comprising eosinophilic refractile deposits within vessel lumina with extension into the intima, with or without an accompanying characteristic granulomatous vasculitic component. Ultrastructural examination of the renal deposits showed fibrillary material within glomerular capillary lumina with unique morphologic features not previously described. Analysis of plasma from several cases revealed a cold-precipitable protein, which in most cases included a monoclonal paraprotein. The laboratory and histologic distinctions between cryofibrinogenemia and cryoglobulinemia are addressed. We provide guidelines for the proper handling of patient specimens in the workup of cryofibrinogenemia.