Background: Trichilemmoma (TL) can occur as a solitary sporadic lesion usually on the face or as multiple facial lesions almost invariably associated with Cowden syndrome (CS). CS is a multisystem disorder caused by a germline inactivating mutation in PTEN (10q23.31), a tumor suppressor gene. We sought to identify PTEN loss by immunohistochemistry (IHC) in sporadic and CS-associated TL to determine whether IHC is a useful tool to assess an individual for CS.

Background: The mechanisms of tumor progression in mycosis fungoides (MF) and Sézary syndrome (SS) are poorly understood. Twist, a transcription factor, is thought to promote solid tumor progression by blocking p53 and inhibiting c-myc-induced apoptosis. Whether Twist expression is correlated to MF/SS stages remains unknown.

Desmoplastic trichoepithelioma is a benign follicular tumor occurring most commonly within facial skin of young and middle aged women, morphologically characterized by a superficial dermal proliferation of basaloid cells growing in narrow strands embedded in a desmoplastic stroma with associated small keratinizing cysts. Desmoplastic trichoepithelioma must be distinguished from other benign epithelial proliferations such as syringoma, microcystic adnexal carcinoma, and infiltrating basal cell carcinoma. Among morphological features useful in that distinction, perineural involvement is considered a feature indicative of malignancy. We present a series of seven desmoplastic trichoepitheliomas with otherwise typical presentation and morphology, nevertheless demonstrating epithelium present in the perineural spaces of adjacent small dermal nerves. Patients ranged in age from 14 to 66 years (mean 44 years). All seven tumors were restricted to dermis, showed strands of basaloid epithelium in desmoplastic stroma, and contained CK20-positive cells. Additionally, five of five examined tumors displayed diffuse expression of p75 neurotrophin receptor. Five patients were followed-up clinically (follow-up time range: 2 months - 4 years). No tumor recurrence was observed in any of these patients. We postulate that perineural involvement is an unusual feature of desmoplastic trichoepithelioma that should not be equated with malignancy or lead to unnecessary over-treatment.

Hypopigmented mycosis fungoides is a relatively uncommon variant of cutaneous lymphoma that is mostly seen in darker skin types. We present a novel and unique clinical presentation in an African-American female patient, consisting of regular hypopigmented annular rings in areas of normal skin and in more typical hypopigmented patches of mycosis fungoides. The lesions appeared diffusely on all extremities, anterior chest, and back. Histopathologic examination showed an atypical lymphocytic infiltrate at the dermal-epidermal junction with epidermotropism and few Pautrier's collections. The patient was otherwise healthy and improved with narrowband ultraviolet (UV)-B. This case represents a presentation of a most unusual variant of hypopigmented mycosis fungoides, for which we propose the name “annular hypopigmented mycosis fungoides.”

Pemphigus foliaceus (PF) represents an autoimmune blistering disease characterized by the disruption of epidermal intercellular adhesion proteins. Clinical findings include superficial crusted erosions in a seborrheic distribution, however the disease can rarely present as an exfoliative erythroderma. Histopathologic findings include acantholysis with cleavage within the granular layer. Direct immunofluorescence studies demonstrate intercellular IgG and complement deposition. We present two patients with a previous diagnosis of psoriasis who presented to our dermatology department with an exfoliative erythroderma, which ultimately proved to be due to PF based on histopathological features, direct immunofluorescence results, and levels of antibodies against desmoglein 1. Both patients responded well to oral prednisone and rituximab. This variant of PF should be entertained in both the clinical differential diagnosis of psoriasiform erythroderma and in the microscopic differential diagnosis of psoriasiform epidermal hyperplasia with focal acantholysis, particularly in patients for whom the clinical history is not classic for psoriasis or for whom conventional psoriasis therapies have not proven beneficial.

In lymph nodes, classical Hodgkin lymphoma can typically be distinguished from non-Hodgkin lymphoma (NHL) by the presence of Hodgkin and Reed-Sternberg cells that co-express CD30 and CD15. However, anaplastic large cell lymphoma (ALCL) and diffuse large B-cell lymphoma (DLBCL) can show identical features, and some cases of classical Hodgkin lymphoma lack CD15 expression, rendering them difficult to differentiate from CD30-positive NHL. The differential diagnosis of cutaneous Hodgkin lymphoma similarly includes ALCL and DLBCL, and, additionally, tumors of mycosis fungoides. Recent studies have shown that classical Hodgkin lymphoma is of B-cell origin in virtually all cases, and shows at least focal weak expression of the B-cell marker PAX5 and often focal weak expression and no expression of the B-cell markers Oct-2 and BOB.1, respectively. All three of these markers are almost invariably absent in T-cell lymphomas and are strongly expressed in B-cell lymphomas. We report a 40-year-old man with classical Hodgkin lymphoma who developed cutaneous nodules. A biopsy from one revealed Hodgkin/Reed-Sternberg cells with a similar immunophenotype to the diagnostic lymph node biopsy, namely CD30+/CD15+, diffusely but weakly PAX5+, focally weakly Oct-2+ and lacking BOB.1 expression, thereby confirming a diagnosis of cutaneous Hodgkin lymphoma. To our knowledge, this is the first report of the expression pattern of the combination of PAX5, Oct-2 and BOB.1 in the context of cutaneous involvement by Hodgkin lymphoma.

Acute primary cutaneous leishmaniasis typically presents microscopically with a lymphohistiocytic infiltrate containing admixed plasma cells, parasitized macrophages and abundant organisms. Tuberculoid granulomatous changes may occur in the later phases of primary infection. A 23-year-old male presented 1 month after visiting Peru with classic clinical findings of acute primary cutaneous leishmaniasis, while histopathology showed a tuberculoid granulomatous process that lacked any organisms in hematoxylin–eosin and fungal stains. Polymerase chain reaction (PCR) analysis and tissue cultures confirmed the diagnosis of cutaneous leishmaniasis with Leishmania (Viannia) panamensis infection. A pauci-organism tuberculoid granulomatous process may uncommonly be the presenting histopathology in the acute infectious phase of cutaneous leishmaniasis. Clinicians and dermatopathologists should be aware of this atypical presentation, which may cause diagnostic confusion and delay proper treatment. PCR testing should be employed in cases with high clinical suspicion when histopathology is not definitive.

Epstein-Barr virus (EBV)-positive mucocutaneous ulcer was recently described as a clinicopathologic entity occurring secondary to iatrogenic or age-related immune suppression. The histopathology of EBV-positive mucocutaneous ulcer reveals a polymorphous infiltrate including atypical large B-cells and Reed-Sternberg-like cells which are CD20-positive, CD30-positive and EBV-positive. The disorder follows an indolent and self-limited course. We report a case of EBV-positive mucocutaneous ulcer secondary to prolonged use of azathioprine for the treatment of pemphigoid and highlight the need for recognition of this disorder by dermatopathologists and dermatologists.

Lipomas are the most common subtype of benign soft tissue neoplasms and can occur anywhere in the body. Differentiation into a diversity of mesenchymal elements, such as blood vessels, fibrous tissue or muscle, is a frequent event. However, the presence of bone or cartilage in these tumors is extraordinarily rare with very few cases reported in the head and neck area. We report a case of an ‘osteochondrolipoma’ of the chest wall, in a young individual, providing a rationale in support of this as a possible and distinctive histologic subtype of lipomas, as well as discussion in the differential diagnosis of this lesion.

Background: Antibodies to CD56 label natural killer cells as well as tissues with neural and neuroendocrine differentiation. Despite its apparently limited distribution, other conditions may unexpectedly show strong CD56 expression.

Pilomatrixomas are benign follicular tumors that occur most commonly in children. Rare multiple or familial pilomatrixomas have been associated with myotonic dystrophy and other disorders. Although sporadic pilomatrixomas and hybrid cutaneous cysts with pilomatrixoma-like features have been observed in some kindreds with Gardner syndrome, an autosomal dominant form of familial adenomatous polyposis, no definitive association has been made with multiple or familial pilomatrixomas. Here we describe two siblings with multiple pilomatrixomas who were also found to have a family history of colonic adenocarcinoma. Genetic testing revealed a mutation in the 5′ portion of the adenomatous polyposis coli (APC) gene, in a region associated with an attenuated APC phenotype. These findings show that multiple pilomatrixomas may be the presenting symptom of patients with APC gene mutations.

We describe a case of blastic primary cutaneous mantle cell lymphoma (MCL) in an 83-year-old male with a complex medical history. The patient presented to his primary care physician with a nodular erythematous skin eruption on his thighs. Histopathologic examination showed a diffuse lymphoid infiltrate of intermediate to large cells that involved the dermis and subcutis but spared the epidermis. Immunohistochemical staining showed expression of CD20, CD5 and cyclin-D1. The lymphoma cells were negative for CD10 and CD23. Fluorescence in situ hybridization (FISH) analysis revealed a characteristic translocation [t(11;14)(q13;q32)], which is diagnostic of MCL. Cutaneous involvement by MCL is typically secondary because of widespread disease, and primary cutaneous MCL can only be diagnosed in the absence of extracutaneous involvement. Primary cutaneous MCL is extremely rare and requires proper clinical staging. In this case, clinical staging revealed no evidence of bone marrow or peripheral blood involvement, and positron emission tomography (PET) scan revealed weak, abnormal uptake only in a few cervical lymph nodes. Because of the lack of disseminated involvement, we favor the lesion to be a primary cutaneous MCL.

Vascular tumors are categorized into benign hemangiomas, frankly malignant angiosarcomas and tumors with intermediate biological behavior (hemangioendotheliomas). The latter group includes hemangioendotheliomas of the epithelioid, kaposiform, retiform and composite subtypes. Furthermore, a heterogeneous group of both benign and intermediate vascular tumors exhibits a peculiar hobnail cell morphology. This heterogeneous group encompasses hobnail hemangioma, retiform hemangioendothelioma, papillary intralymphatic angioendothelioma and a subset of angiosarcoma. We herein present a case of a cutaneous vascular neoplasm with hobnail morphology and unusual gross features.

Brooke-Spiegler syndrome represents an autosomal dominant disease characterized by the occurrence of multiple cylindromas, trichoepitheliomas and (sporadically) spiroadenomas. Patients with Brooke-Spiegler syndrome are also at risk of developing tumors of the major and minor salivary glands. Patients with Brooke-Spiegler syndrome have various mutations in the CYLD gene, a tumor-suppressor gene located on chromosome 16q. To date, 68 unique CYLD mutations have been identified. We describe two families with Brooke-Spiegler syndrome, one with familial cylindromatosis and one with multiple familial trichoepithelioma, which showed wide inter-family phenotypic variability. Analysis of germline mutations of the CYLD and PTCH genes was performed using peripheral blood. In addition, formalin-fixed paraffin-embedded tumor samples were analyzed for PTCH somatic mutations and cylindroma cell cultures were obtained directly from patients for further growth and analysis. Clinically, the major features of Brooke-Spiegler syndrome include the presence of heterogeneous skin tumors and wide inter- and intra-familial phenotypic variability. Histopathologically, both cylindromas and trichoepitheliomas were found in affected individuals. Mutations or loss of heterozygosity was not found in CYLD and PTCH genes. In CYLD and PTCH mutation-negative patients, other genes may be affected and further studies are needed to clarify whether these patients may be affected by de novo germline mutations.

We present a patient with a 2-cm spiradenocarcinoma of the left arm resembling low-grade salivary gland basal cell adenocarcinoma. In addition to showing attributes of conventional spiradenoma, the benign component showed prominent areas of cystic change with focal apocrine differentiation, glands with and without mucinous differentiation, clear cell change and focal adenoid cystic carcinoma-like areas. The malignant component was composed of nodules of basaloid cells arranged in sheets with variable tendency to luminal differentiation. The nuclear atypia was low-grade, and the mitotic index was high in the malignant component (to 8/10 high power fields). Immunohistochemically, there was diffuse but variable positivity for cytokeratin 7 in both the benign and malignant components. Epithelial membrane antigen was focally positive, highlighting cells with ductal (luminal) differentiation. Expression of p63 was observed in 50 and 80% of the cells in the benign and malignant components, respectively. Calponin was negative. The proliferative index (MIB-1/Ki-67) was <3% in the benign component and up to 10% in the malignant component. Although the malignant component displayed patchy areas with nuclear p53 immunoreactivity with variable intensity, no mutation in the TP53 gene was identified.

Scedosporium apiospermum, the asexual stage of Pseudoallescheria boydii, is a fungus ubiquitous in soil as well as organically polluted areas, where nitrogen-containing compounds are abundant. It is an emerging opportunistic pathogen that can range from cutaneous to disseminated infection and can be fatal within months of diagnosis. Here we present a case of disseminated S. apiospermum infection with cutaneous manifestations in a 59-year-old woman with myelodysplastic syndrome, in remission from chronic lymphocytic leukemia, presented with pneumonia and deteriorating mental status. An X-ray computed tomography scan showed three non-contrast-enhancing hypodensities affecting the brain. Many erythematous, indurated skin lesions, measuring 3–5 mm in diameter, were noted on her chest, shoulders and arms. Biopsies were submitted for culture and histology. Histopathologic examination revealed superficial and deep perivascular and periadnexal inflammatory infiltrates of lymphocytes and neutrophils. Scattered collections of fungal organisms were noted near the eccrine glands. The periodic acid Schiff with diastase stain showed the presence of variable sized spores and hyphae with some acute angle branching. Both tissue and blood cultures were positive for a single Scedosporium species. Histologically, eccrine or peri-eccrine involvement by fungi may be an important finding for Scedosporium infection of the skin.

Terminology regarding classification of benign lesions with prominent eccrine differentiation can be confusing as these lesions can have overlapping clinical and histologic characteristics. In this report, we examine a case and review of the literature to suggest that these entities may be better classified as a spectrum of benign lesions with overlapping features rather than distinct entities. We describe a case of an acantholytic dyskeratotic epidermal nevus with eccrine differentiation on the back of a 2-year-old patient. We then discuss the classic clinical and histologic presentations of eccrine nevi and epidermal nevi with eccrine differentiation as they relate to each other and to our case.

Background:  We planned this study to analyze probable associations between p53, cyclinD1, Ki67 and histopathological features in basal cell carcinomas (BCC).

Background: The histopathologic pattern of clonal seborrheic keratosis (SK) is quite similar to the nested pattern of pagetoid Bowen's disease [squamous cell carcinoma in situ (SCCIS)], and differentiation between the two can be challenging, especially when only small pieces are available for interpretation.

Background: Secondary angiosarcoma and benign but microscopically atypical vascular proliferations (herein referred to as atypical vascular lesion or AVL) are rare consequences of radiation therapy and/or chronic lymphedema most commonly seen in breast cancer patients. Differentiating angiosarcoma from AVL can be difficult due to overlapping clinical and microscopic features. Recently, amplification of MYC has been associated with 55–100% of secondary angiosarcomas but is reportedly absent in AVL. We examined a series of secondary angiosarcoma and AVL for MYC amplification by fluorescence in situ hybridization (FISH) and expression by immunohistochemistry to investigate the diagnostic utility for discriminating angiosarcoma from AVL.

Background: Distinguishing keratoacanthoma (KA) and hypertrophic lichen planus (LP) histopathologically can be difficult, and the challenge is compounded by the tendency of KA to arise in association with hypertrophic LP.

Background: Cutaneous leishmaniasis displays considerable variation in its histopathological and clinical presentation. Clinically, it progresses from a papule into a painless ulcerated and crusted nodule/papule. Microscopically, it progresses from sheets of amastigote-filled histiocytes to granulomatous inflammation.

Primary cutaneous amyloidosis includes several forms of localized amyloidosis characterized by superficial amyloid deposits occurring at or near the dermal–epidermal junction in the absence of systemic involvement. Primary cutaneous amyloidosis of the auricular concha and external ear represents a rarely described variant. There have been 27 cases reported in the English language literature, and herein we report 17 additional cases. This article demonstrates that the amyloid observed in this context is generally positive for Congo red, crystal violet and thioflavin T. It also expresses cytokeratin 34ßE12 via immunohistochemistry. Our immunohistochemical results and review of the literature suggest that the amyloid in amyloidosis of the external ear is the result of basal keratinocyte degeneration and does not signify deposition from a systemic or generalized process.

The clinical and histopathological features of cutaneous herpes simplex virus (HSV) infection have been well described. Genital herpetic infections are largely induced by HSV type 2, but 30% of cases can be caused by HSV type 1. Immunocompromised patients are known to exhibit atypical patterns of clinical presentation with variable lesion morphology and anatomic location. A subset of patients may show morphology such as nodules or verrucous lesions. Analogously, some biopsy specimens may show unusual microscopical features, such as a lack of keratinocyte cytopathology, lymphocyte infiltration or vasculopathic changes that are expected irrespective of the patient's immune status. We present the case of a patient carrying a previous diagnosis of pemphigus vulgaris, status posttreatment with methotrexate and prednisone, who developed a perineal ulcer exhibiting significant numbers of plasma cells, many of which were cytologically atypical. This morphology was suggestive of a hematopoietic malignancy. Immunoperoxidase staining for HSV decorated a focal collection of keratinocytes that lacked appreciable viral changes expected of HSV infection.

Primary effusion lymphoma, a human herpesvirus 8 (HHV8)-associated lymphoma, is uncommon, and it is usually seen in human immunodeficiency virus (HIV)-infected patients. It presents as a body cavity-based lymphomatous effusion, but several cases of the so-called solid primary effusion lymphoma presenting as solid tumors without associated lymphomatous effusion have been reported. They have similar clinical, histopathological and immunophenotypical features. Most of them have a B-cell genotype. This suggests the solid variant may represent a clinicopathological spectrum of primary effusion lymphoma. We report a case of HHV8-associated lymphoma histopathologically and immunophenotypically mimicking cutaneous anaplastic large cell lymphoma. The patient was a 31-year-old HIV-seropositive man presenting with skin nodules over his right thigh. Biopsy of the nodules showed anaplastic large cells infiltrating the dermis. These malignant cells strongly expressed CD3, CD30 and CD43. Cutaneous anaplastic large T-cell lymphoma was initially diagnosed, but further tests, including immunoreactivity for HHV8 protein and clonal rearrangements of immunoglobulin genes, confirmed the diagnosis of HHV8-associated B-cell lymphoma with aberrant T-cell marker expression. This case provides an example of solid primary effusion lymphoma mimicking cutaneous anaplastic large T-cell lymphoma and highlights the importance of HHV8 immunohistochemistry and molecular tests in the diagnosis of HHV8-associated lymphoma with a cutaneous presentation.

A 62-year-old man presented with a 2-year history of a 2-cm cystic mass involving his occiput. There had been recent enlargement, and the clinical impression was that of a pilar cyst. Histopathological sections showed a partially dermal solid and cystic proliferation. The tumor contained areas of glandular differentiation with cuboidal to columnar cells lining luminal and cystic spaces. A concurrent spindle cell proliferation was seen interspersed between glands and also formed broad, cellular sheets of cells. The stroma was sclerotic and without chondroid or myxoid elements. Immunohistochemistry showed that the spindled cells expressed S100 protein, cytokeratin and smooth muscle myosin. The immunohistochemical profile and the relationship with ductal elements supported myoepithelial differentiation. The proliferation warranted the diagnosis of myoepithelioma arising from a hidradenoma, which to our knowledge has not been previously described. In addition to discussing this case, we provide a brief review of epithelial–myoepithelial neoplasms encountered in the skin.

Subungual melanoma commonly presents with solitary longitudinal melanonychia. Herein, we report the case of a patient with subungual melanoma who developed involvement of three digits by three independent primary melanomas. A 98-year-old male patient presented with a two-year history of longitudinal melanonychia on three different fingernails. Histopathologically, all three lesions were proved to be melanoma. To our knowledge, this is the first reported case in which three subungual melanomas developed in one patient. Our case indicates that that not all examples of multiple longitudinal melanonychia represent benign lesions.

A 59-year-old female with rheumatoid arthritis on etanercept therapy presented with a 7-cm-large subcutaneous forearm mass. Multiple smaller nodules subsequently developed on the upper and lower extremities. Except for a new cough, the patient was systemically well. Biopsy of the mass showed sarcoidal type granulomatous inflammation with nodular aggregations of non-necrotizing epithelioid histiocytes in the subcutis. A chest computed tomography (CT) scan showed mediastinal adenopathy consistent with pulmonary sarcoidosis. Etanercept was discontinued, and the patient was started on adalimumab for rheumatoid arthritis control. The cutaneous nodules fully resolved in 6 months with no additional treatment. A 4-month follow-up CT scan showed significant regression of mediastinal adenopathy. The patient has since been maintained on adalimumab therapy for 2 years with no recurrence of sarcoid-like manifestations. Biologic response modifiers targeting tumor necrosis factor alpha (TNFα) are effective treatments of chronic inflammatory conditions such as rheumatoid arthritis and psoriasis. TNFα represents a major cytokine in granuloma formation, and TNFα inhibitors are sometimes efficacious in the treatment of sarcoidosis. Paradoxically, there is a small volume of literature implicating TNFα inhibitors in the development of sarcoid-like disease. We present this case to promote the recognition of TNFα inhibitor-induced sarcoidosis and to illustrate the wide clinicopathologic differential of sarcoidal type granulomas.

Granulomatous cutaneous reactions are well described in association with T-cell non-Hodgkin lymphoma and Hodgkin lymphoma, but are rarely seen in association with B-cell non-Hodgkin lymphoma or leukemia. We report a case of a 65-year-old woman with B-cell chronic lymphocytic leukemia (CLL)/small lymphocytic lymphoma (SLL) who presented with multiple, tender, firm pink papules on the face, upper trunk and upper extremities 6 years after diagnosis of CLL. Biopsy revealed both palisading granulomatous dermatitis consistent with actinic granuloma and a dense perivascular lymphocytic infiltrate consistent with the patient's known history of leukemia. This is an unusual manifestation of cutaneous B-cell CLL that is rarely seen.