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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.

In 1990, an international grading scheme for the grading of pulmonary allograft rejection was adopted by the International Society for Heart and Lung Transplantation (ISHLT) and was modified in 1995 by an expanded group of pathologists. The original and revised classifications have served the lung transplant community well, facilitating communication between transplant centers with regard to both patient management and research. In 2006, under the direction of the ISHLT, a multi-disciplinary review of the biopsy grading system was undertaken to update the scheme, address inconsistencies of use, and consider the current knowledge of antibody-mediated rejection in the lung. This article summarizes the revised consensus classification of lung allograft rejection. In brief, acute rejection is based on perivascular and interstitial mononuclear infiltrates, Grade A0 (none), Grade A1 (minimal), Grade A2 (mild), Grade A3 (moderate) and Grade A4 (severe), as previously. The revised (R) categories of small airways inflammation, lymphocytic bronchiolitis, are as follows: Grade B0 (none), Grade B1R (low grade, 1996, B1 and B2), Grade B2R (high grade, 1996, B3 and B4) and BX (ungradeable). Chronic rejection, obliterative bronchiolitis (Grade C), is described as present (C1) or absent (C0), without reference to presence of inflammatory activity. Chronic vascular rejection is unchanged as Grade D. Recommendations are made for the evaluation of antibody-mediated rejection, recognizing that this is a controversial entity in the lung, less well developed and understood than in other solid-organ grafts, and with no consensus reached on diagnostic features. Differential diagnoses of acute rejection, airway inflammation and chronic rejection are described and technical considerations revisited. This consensus revision of the working formulation was approved by the ISHLT board of directors in April 2007.

Since its first description in 1930, the pathogenesis of pyoderma gangrenosum (PG) has remained obscure even as an ever-widening array of systemic diseases has been described in association with it. The histopathologic distinction of PG from other ulcerative processes with dermal neutrophilia is challenging and at times impossible. In consequence, when confronted with a biopsy from such a lesion, the pathologist has an obligation to obtain a full and detailed clinical history. In short, as a diagnosis of PG does not hinge exclusively upon the biopsy findings in isolation from other studies, a solid knowledge of the clinical features, the systemic disease associations and the differential diagnosis will help the pathologist to avoid diagnostic pitfalls or the generation of a report which is non-contributory to patient care. In this review, we describe in detail the different clinicopathologic forms of PG, summarize the diseases associated with this process in the literature and in our experience, and briefly review the treatment options.