Acral lymphomatoid papulosis: Report of five cases, differential diagnosis, and review.

Acral lymphomatoid papulosis (a-LyP) is a rare clinical variant of LyP whose diagnosis may be challenging. A case series of a-LyP was studied clinically, histopathologically, immunohistochemically, and from molecular point of view. Including ours, 25 cases of a-LyP have so far been reported. Clinically, a-LyP may present as acral involvement exclusively, in combination with mucosal lesions, (in itself a rare presentation), or in association with conventional LyP. The age of presentation was slightly higher than that of conventional LyP (55 vs 45 years) and a male predominance has been observed, as usually reported. Histopathologically, no morphological differences exclusively from conventional LyP were observed. LyP types A and E were the main variants. We describe for the first time one case of type D a-LyP. Acral LyP is a rare entity and correct diagnosis can only be reached with clinical and histopathological correlation, to avoid aggressive treatment of this indolent lymphoproliferative disorder.

Immunohistochemical Demonstration of Parvovirus B19 Viral Protein 2 in Periflexural Exanthema in an Adult, Supporting Antibody-Dependent Enhancement as Means of Endothelial Uptake of the Virus.

Human parvovirus B19 (B19V) causes a number of skin exanthemas and has been related to both cutaneous and systemic diseases. Tropism of the virus for the rapidly proliferating erythroid progenitor cells in the bone marrow and fetal liver explains the pathogenesis of anemia and fetal hydrops. The cutaneous lesions of erythema infectiosum and other B19V-related exanthemas have been attributed to the deposition of immune complexes in the skin. We report on the immunohistochemical detection of B19V protein in the cytoplasm of dermal endothelial cells in a case of periflexural exanthema in a 28-year-old woman. An antibody-dependent enhancement mechanism of entry has been suggested for B19V in myocardial endothelial cells and could also be involved in B19V-related exanthemas.

Primary cutaneous dermal mucinosis on herpes zoster scars.

The term isotopic response refers to the appearance of a new skin disease at the site of another unrelated and already healed skin disorder. Often, the first disease is herpes zoster (HZ). Several cutaneous reactions have been described in a dermatome recently affected by HZ. We present the case of a 33-year-old man who developed whitish papules with a zosteriform distribution on HZ scars. Histopathologic study with hematoxylin and eosin and Alcian blue (pH 2.5) staining demonstrated abundant deposits of mucin interstitially arranged between collagen bundles of the papillary dermis. Cutaneous dermal mucinosis as a postherpetic isotopic response is rare, but it should be added to the list of cutaneous reactions arising in HZ scars.

Extracavitary primary effusion lymphoma presenting as a cutaneous tumor: a case report and literature review.

Primary effusion lymphoma is an unusual form of aggressive B-cell lymphoma universally associated with human herpesvirus 8 (HHV8) that involves mostly human immunodeficiency virus (HIV)-infected patients. Characteristically, it presents as a malignant serous effusion involving body cavities, but without associated tumor mass. Exceptionally, HHV8-positive lymphomas with features identical to primary effusion lymphoma may present as mass lesions in the absence of cavity effusions along the course of the disease, and are regarded as extracavitary or solid variants of the disorder. These rare forms are extremely rare in the skin. We report a case of extracavitary primary effusion lymphoma arising in a HIV-infected male, who presented with two subcutaneous masses involving the skin of the abdominal and inguinal regions as the first manifestation of the process. Kaposi sarcoma was not present in the skin surface or mucous membranes. Extensive studies failed to demonstrate involvement of other organs and the case was considered as an example of extracavitary primary effusion lymphoma originating primarily in the skin. Herein, we review the few reported cases of solid primary effusion lymphoma involving the skin in order to delineate the clinicopathologic, immunohistochemical and molecular characteristics of this rare lymphoma in the skin.

Essential thrombocythemia presenting as localized livedo reticularis.

Essential thrombocythemia is a chronic myeloproliferative disorder characterized by a persistent and absolute increase in the peripheral platelet count (>600,000/mm) in the absence of another underlying disorder. From a clinical point of view, it is characterized by thrombotic manifestations that primarily involve the central nervous system as strokes and transient ischemic attacks and also affects other systems, causing gastrointestinal hemorrhages and arterial or venous thrombosis. Cutaneous manifestations may complicate essential thrombocythemia, but they may be a helpful guide to the diagnosis. These manifestations appear up to 22% of patients and may even be the presenting sign of the disease in up to 10% of them. We present a case of a previously healthy woman who was diagnosed with essential thrombocythemia after the onset of localized livedo reticularis. The case was immunohistochemically studied, supporting the role of the increased platelet number in the pathogenesis of the livedo reticularis lesions.

Postirradiation pseudosclerodermatous panniculitis: three new cases with additional histopathologic features supporting the radiotherapy etiology.

Postirradiation pseudosclerodermatous panniculitis is a rare panniculitic disorder induced by radiotherapy. Clinically, it consists of an indurate plaque localized on the irradiated area that may appear months or even years after radiotherapy was administered. Histopathologically, postirradiation pseudosclerodermatous panniculitis is characterized by a mostly lobular panniculitis without vasculitis, with lipophagic granuloma involving the fat lobules, a variable inflammatory infiltrate of lymphocytes and plasma cells and sclerotic thickening of the connective tissue septa of the subcutis. We report 3 additional cases of this rare variant of panniculitis, in which besides the panniculitis findings, dermal vessels showed sclerotic vessel walls and atypical bizarre fibroblasts with large pleomorphic and hyperchromatic nuclei were interstitially arranged between collagen bundles of the dermis. These dermal findings represent additional histopathologic features supporting the pathogenic role of the radiotherapy in the development of this rare variant of panniculitis.

Pseudoxanthoma elasticum-like papillary dermal elastolysis: immunohistochemical study using elastic fiber cross-reactivity with an antibody against amyloid P component.

Pseudoxanthoma elasticum (PXE)-like papillary dermal elastolysis is a rare disorder clinically characterized by multiple, asymptomatic nonfollicular papules, yellow or flesh colored, grouped to form plaques with cobblestone appearance. These plaques are arranged symmetrically on the neck and supraclavicular areas of adult or elderly women, closely resembling the lesions of PXE. Histopathologically, the lesions are characterized by a band-like area of elastolysis along the papillary dermis. We report 2 cases of PXE-like papillary dermal elastolysis, in which the anomalies of the elastic tissue were immunohistochemically investigated with an antibody to the amyloid P component. This immunostaining demonstrated a band-like loss of elastic tissue along the papillary dermis. No clumping, fragmentation, or calcification of the elastic tissue was seen. We also review the literature about this rare process and discuss the differential diagnosis with other elastic tissue disorders that may show similar clinical and/or histopathologic findings.

Familial acral localized late-onset focal dermal elastosis.

Late-onset focal dermal elastosis is a rare disorder of elastic tissue, characterized by a local accumulation of elastic fibers in the mid and deep reticular dermis. This disorder occurs mainly in elderly people and consists of multiple yellow papules that are typically distributed on the sides of the neck and flexural areas, closely resembling pseudoxanthoma elasticum from the clinical point of view. We report 2 sisters who have presented with a 20-year history of multiple yellow papules, mainly located on the dorsum of their hands. They also had few lesions of similar morphology scattered on the anterior aspects of their wrists, thighs, and lower abdomen. Histopathologic study demonstrated a focal increase in thick, interlacing elastic fibers in the mid and deep reticular dermis. The most striking features of our cases were the early age of clinical presentation, the familial involvement, and the predominantly acral distribution of the lesions.

Lichen scrofulosorum mimicking lichen planus.

Lichen scrofulosorum is the most uncommon clinicopathologic variant of the tuberculids. Usually, the eruption appears in children and adolescents with strong immune sensitivity to Mycobacterium tuberculosis and consists of tiny follicular papules, closely resembling lichen nitidus. We report a case of lichen scrofulosorum in an adult male with active cervical scrofuloderma who developed lesions of lichen scrofulosorum mimicking clinically lichen planus. Histopathologic study demonstrated granulomas around the hair follicles, although acid-fast bacilli stains, immunohistochemical stain for mycobacteria, polymerase chain reaction investigations and cultures failed to demonstrate Mycobacterium tuberculosis in the cutaneous lesions. The most striking features of the reported case were the onset of the eruption in an adult patient and the clinical appearance of the lesions, resembling lichen planus.

Diffuse lower limb lipoatrophy.

Lipoatrophic panniculitis is the term used to describe those panniculitides in which atrophy of the subcutaneous fat is the main residual lesion. They can be classified as primary or secondary. Primary lipoatrophic panniculitis is idiopathic, whereas secondary lipoatrophic panniculitides include those because of infection, malignancy, pancreatic disorders or connective tissue diseases. Usually, these entities are characterized by the appearance of tender, erythematous nodules or plaques that resolve leaving one or several localized areas with loss of subcutaneous fat. We report a 76-year-old female who developed diffuse and symmetric lipoatrophy of lower limbs after an extensive inflammatory process affecting both extremities from thighs to ankles. Histopathologic assessment revealed a lobular panniculitis with a lymphohistiocytic infiltrate, foamy macrophages and lipophagic granuloma formation. The most striking feature in our patient was the clinical presentation as a symmetrical diffuse inflammatory process resulting in lipoatrophy of the lower limbs.