Merkel cell carcinoma arising within a poroma: report of two cases.

Merkel cell carcinoma (MCC) has been reported in association with other types of cutaneous neoplasms within the same lesion, including squamous cell carcinoma, Bowen's disease, actinic keratosis, follicular cysts, trichoblastoma and lentigo maligna, among others. However, the association of MCC and sweat gland tumors has never been described in the literature. We report two unique cases of MCC that developed within cutaneous poromas. A 56-year-old male (Patient 1) and an 81-year-old female (Patient 2) presented with nodules on the upper arm and lower back, respectively. Histopathologic study of both cases revealed a tumor in the dermis composed of poroid and cuticular cells intermingled with a proliferation of small round cells that showed characteristic histopathological and immunohistochemical features of MCC. In both cases, the two neoplasms were tightly admixed and distinct, suggesting that the MCC could have developed within a previously existing poroma. No morphological features of transition between the two tumors were seen. Neoplastic cells of MCC expressed immunoreactivity for chromogranin, synaptophysin, neuron-specific enolase, CAM 5.2 and cytokeratin 20, the last two markers showing the characteristic paranuclear dot-like pattern. In contrast, the poroma cells only expressed cytokeratin MNF116. Metastatic deposits were not identified in the regional lymph nodes or distantly.

Sebocyte-like cell primary cutaneous melanoma: a rare cytologic variant of malignant melanoma.

Although rising incidence rates of cutaneous melanoma have been observed during the last 4 decades in white populations worldwide, the sebocyte-like cell variant has been described only twice in the literature to date. In our case, a 64-year-old man presented for evaluation of a changing pigmented lesion on the left upper back. Excision of the lesion revealed an invasive melanoma with a Breslow depth of 3.3 mm. Microscopic sections showed a predominantly dermal-based tumor composed of sheets and nests of enlarged epithelioid melanocytes, most of which showed an uncommon phenotype with multivacuolated cytoplasms and scalloped nuclei, features that gave them a strong resemblance to mature sebocytes. The lesional cells expressed S100 protein, Melan-A, and p16, whereas adipophilin was positive only within the sebocyte-like component of the neoplasm and showed focal nonspecific staining. The patient's sentinel lymph node biopsy was positive for micrometastases, although a subsequent position emission tomography scan was unremarkable. Sebocyte-like melanocytes are a rare distinctive type of melanocytes that can be found mostly in benign but also in malignant melanocytic lesions. They usually present focally within the lesions and, therefore, do not represent a diagnostic problem in nevus or primary cutaneous melanoma. However, when sebocyte-like melanocytes are the main cellular component of a melanocytic lesion or when they are found in the context of metastatic melanoma, they may create a potential diagnostic pitfall; for this reason, awareness of this cell type is important.

Immunohistochemistry in the diagnosis of cutaneous viral infections- part II: cutaneous viral infections by parvoviruses, poxviruses, paramyxoviridae, picornaviridae, retroviruses and filoviruses.

BACKGROUND: Cutaneous viral infections are increasing in recent years, particularly in immunocompromised patients. OBJECTIVE: Immunohistochemistry (IHC) provides a rapid and helpful tool that can be applied to confirm the diagnosis of specific viral infections that may be difficult to diagnose with certainty using routine microscopy alone. METHODS: Several immunostains that are useful in histopathology have been reviewed and tested in cutaneous samples of viral infections. Emphasis is placed on new stains and novel uses of existing stains. RESULTS: This article is an up-to-date overview of the potential uses of IHC in the histopathologic diagnosis of cutaneous viral infections by parvoviruses, polyomaviruses, poxviruses, paramyxoviridae, picornaviridae, retroviruses, and filoviruses. LIMITATIONS: Specific monoclonal antibodies are commercially available only for some members of these virus families. CONCLUSIONS: IHC may assist dermatopathologists to appropriately diagnose viral infections by parvoviruses, polyomaviruses, poxviruses, paramyxoviridae, picornaviridae, retroviruses, and filoviruses.

Immunohistochemistry in the diagnosis of cutaneous viral infections--part I. Cutaneous viral infections by herpesviruses and papillomaviruses.

BACKGROUND: Cutaneous viral infections are of increasing clinical importance, particularly in patients who are immunocompromised. OBJECTIVE: The use of immunohistochemistry (IHC) in the diagnosis of cutaneous infections provides a rapid morphological diagnosis and can be applied to confirm the diagnosis of specific viral infections that may be difficult to diagnose with certainty using routine microscopy alone, thus facilitating clinical decisions in patient care. METHODS: Several immunostains for specific viruses that have been useful in dermatopathology are reviewed. Emphasis is placed on new stains and novel uses of existing stains. RESULTS: This article is an up-to-date overview of the potential uses and limitations of IHC in the histopathologic diagnosis of cutaneous viral infections by herpesviruses and papillomaviruses. LIMITATIONS: Whereas specific monoclonal antibodies effectively distinguish infections by herpes simplex virus-1, herpes simplex virus-2, varicella zoster virus, Epstein-Barr virus, and cytomegalovirus, IHC does not distinguish between the 120 antigenically distinct strains of human papillomavirus. CONCLUSIONS: IHC may assist dermatopathologists to appropriately diagnose viral infections caused by herpesviruses and papillomaviruses.

Metastatic melanoma in association with a giant congenital melanocytic nevus in an adult: controversial CGH findings.

Giant congenital melanocytic nevi (GCMNs) represent a distress to patients for 2 reasons: one is disfigurement, and the other is the increased risk of developing secondary melanocytic tumors, such as benign proliferative nodules (BPNs) and malignant melanoma (MM). BPN present as a rapid growth nodule arising within a congenital melanocytic nevus (CMN) that often ulcerates, occurs in children younger than 2 years of age. BPNs arising within a CMN are exceedingly rare after childhood, and very few cases have been described in adults. Despite the worrisome clinical and histologic findings of BPN, most laboratory investigations seem to support their benignity. The distinction between MM and BPN is extremely important, but the histopathology of BPN of GCMN can be a challenge to differentiate from MM. In the recent years, molecular tests that investigate DNA copy number alterations such as fluorescence in situ hybridization and comparative genomic hybridization have shown promise to help guide the diagnosis of ambiguous melanocytic proliferations arising within CMNs. We report the case of a 22-year-old woman with a nodule arising in a GCMN and with an axillary mass suggesting a nodal metastasis of melanoma, and discuss the unusual clinical, histopathologic, and molecular findings that make this case particularly interesting.

Frontal fibrosing alopecia: a multicenter review of 355 patients.

BACKGROUND: To our knowledge, there are no large multicenter studies concerning frontal fibrosing alopecia (FFA) that could give clues about its pathogenesis and best treatment. OBJECTIVE: We sought to describe the epidemiology, comorbidities, clinical presentation, diagnostic findings, and therapeutic choices in a large series of patients with FFA. METHODS: This retrospective multicenter study included patients given the diagnosis of FFA. Clinical severity was classified based on the recession of the frontotemporal hairline. RESULTS: In all, 355 patients (343 women [49 premenopausal] and 12 men) with a mean age of 61 years (range 23-86) were included. Early menopause was detected in 49 patients (14%), whereas 46 (13%) had undergone hysterectomy. Severe FFA was observed in 131 patients (37%). Independent factors associated with severe FFA after multivariate analysis were: eyelash loss, facial papules, and body hair involvement. Eyebrow loss as the initial clinical presentation was associated with mild forms. Antiandrogens such as finasteride and dutasteride were used in 111 patients (31%), with improvement in 52 (47%) and stabilization in 59 (53%). LIMITATIONS: The retrospective design is a limitation. CONCLUSIONS: Eyelash loss, facial papules, and body hair involvement were associated with severe FFA. Antiandrogens were the most useful treatment.

Cutaneous deposits.

: The cutaneous deposition disorders are a group of unrelated conditions characterized by the accumulation of either endogenous or exogenous substances within the skin. These cutaneous deposits are substances that are not normal constituents of the skin and are laid down usually in the dermis, but also in the subcutis, in a variety of different circumstances. There are 5 broad categories of cutaneous deposits. The first group includes calcium salts, bone, and cartilage. The second category includes the hyaline deposits that may be seen in the dermis in several metabolic disorders, such as amyloidosis, gout, porphyria, and lipoid proteinosis. The third category includes various pigments, heavy metals, and complex drug pigments. The fourth category, cutaneous implants, includes substances that are inserted into the skin for cosmetic purposes. The fifth category includes miscellaneous substances, such as oxalate crystals and fiberglass. In this article, the authors review the clinicopathologic characteristics of cutaneous deposition diseases, classify the different types of cutaneous deposits, and identify all the histopathologic features that may assist in diagnosing the origin of a cutaneous deposit.

A rare case of primary cutaneous plasmacytoma-like lymphoproliferative disorder following renal transplantation.

Post-transplant lymphoproliferative disorder (PTLD) is a lymphoid proliferation that develops as a complication of solid organ or bone marrow transplants. PTLD limited to the skin is very rare. Plasmacytoma-like PTLD is an uncommon variant of monomorphic PTLD. Its presentation in the skin is extraordinary with very few cases reported in the literature. We report a new case of plasmacytoma-like PTLD presenting as multiple skin nodules on the leg of a 74-year-old kidney transplant recipient. Histopathologic and immunohistochemical examination of one nodule revealed atypical plasmacytoid and plasmablastic cells that showed kappa light chain restriction and stained positive for CD138. Staging investigations excluded extracutaneous manifestations of the disease. This case is unusual for several reasons including involvement limited to the skin, plasmacytoid phenotype of the tumor, presentation 18 years following transplantation and Epstein-Barr virus negativity.

Cytomegalovirus-induced cutaneous microangiopathy manifesting as lower limb ischemia in a human immunodeficiency virus-infected patient.

Cutaneous infections by cytomegalovirus (CMV) are rare and often difficult to diagnose both clinically and histopathologically. A wide range of different clinical manifestations have been described in the literature, especially in immunosuppressed patients. CMV-induced thrombosis has also been reported in these patients, and various mechanisms have been proposed to explain the role of CMV in the thrombotic process, including direct damage of the endothelial cells, activation of coagulation factors and inducing the production of antiphospholipid antibodies. We present the case of a human immunodeficiency virus (HIV)-infected woman who developed distal ischemic lesions of the lower extremities during a generalized CMV infection. We discuss the role of CMV and antiphospholipid antibodies in the pathogenesis of thrombosis in immunosuppressed patients.

Foreign Body Granulomas.

A large list of foreign substances may penetrate the skin and induce a foreign body granulomatous reaction. These particles can enter the skin by voluntary reasons or be caused by accidental inclusion of external substances secondary to cutaneous trauma. In these cases, foreign body granulomas are formed around such disparate substances as starch, cactus bristles, wood splinters, suture material, pencil lead, artificial hair, or insect mouthparts. The purpose of this article is to update dermatologists, pathologists, and other physicians on the most recent etiopathogenesis, clinical presentations, systemic associations, evaluation, and evidence-based management concerning foreign body granulomatous reactions of skin.