Primary Cutaneous Anaplastic Large Cell Lymphoma-A Review of Clinical, Morphological, Immunohistochemical, and Molecular Features.

Primary cutaneous anaplastic large cell lymphoma (ALCL) is the second most common cutaneous T-cell lymphoma after mycosis fungoides and belongs to the spectrum of cutaneous CD30+ T-cell lymphoproliferative disorders. Although primary cutaneous ALCL usually presents as a localized nodule or papule with or without ulceration, multifocal lesions may occur in up to 20% of cases. Histologically, primary cutaneous ALCL consists of a diffuse dermal infiltrate of medium to large anaplastic/pleomorphic cells with abundant amphophilic-to-eosinophilic cytoplasm, horseshoe-shaped nuclei, strong and diffuse expression of CD30, and with focal or no epidermotropism. The neoplastic infiltrate may show angiocentric distribution and may extend to the subcutis. Patients with localized or multifocal disease have a similar prognosis with a 10-year overall survival rate of 90%. Approximately 30% of primary cutaneous ALCLs harbor a DUSP22 (6p25.3) gene rearrangement that results in decreased expression of this dual-specific phosphatase, decreased STAT3 activation, and decreased activity of immune and autoimmune-mediated mechanisms regulated by T-cells.

[Poorly differentiated synovial sarcoma of the chest wall with rhabdoid features]. / Sarcoma sinovial pobremente diferenciado de pared del tórax con características rabdoides.

We report a rare case of a poorly differentiated synovial sarcoma (SS) with rhabdoid features. A 33-year-old woman was referred to our hospital with a chest wall tumor. MRI revealed a diffuse mass that invaded the pleura and extended into the esophagus, aorta, diaphragm and pancreas. Histopathological examination of the neoplasm showed it to be composed of sheets of small/medium cells with rhabdoid morphology, consisting of round, eccentrically localized nuclei, conspicuous nucleoli, and eosinophilic cytoplasm. Immunohistochemical studies demonstrated the tumor cells to be positive for TLE1, Bcl-2, EMA, CAM5.2, CD138 and CD56 and negative for desmin, smooth muscle actin or S100 protein. Fluorescent in-situ hybridization technique, performed on the paraffin section, showed SS18 gene rearrangement in the nuclei of the tumor cells. Poorly differentiated SS with "rhabdoid" features was diagnosed. This is only the 8th case of a SS with "rhabdoid" features reported to date.

Validation of HIV-1 MA Shell Structural Arrangements and Env Protein Interactions Predict a Role of the MA Shell in Viral Maturation.

The molecular structure of the type 1 human immunodeficiency virus (HIV-1) is tightly linked to the mechanism of viral entry. The spike envelope (Env) glycoproteins and their interaction with the underlying matrix (MA) shell have emerged as key components of the entry mechanism. Microscopy evidence suggests that the MA shell does not span the entire inner lipid surface of the virus, producing a region of the virus that completely lacks an MA shell. Interestingly, evidence also suggests that Env proteins cluster during viral maturation and, thus, it is likely that this event takes place in the region of the virus that lacks an MA shell. We have previously called this part of the virus a fusion hub to highlight its importance during viral entry. While the structure of the MA shell is in contention due to the unaddressed inconsistencies between its reported hexagonal arrangement and the physical plausibility of such a structure, it is possible that a limited number of MA hexagons could form. In this study, we measured the size of the fusion hub by analysing the cryo-EM maps of eight HIV-1 particles and measured the size of the MA shell gap to be 66.3 nm ± 15.0 nm. We also validated the feasibility of the hexagonal MA shell arrangement in six reported structures and determined the plausible components of these structures that do not violate geometrical limitations. We also examined the cytosolic domain of Env proteins and discovered a possible interaction between adjacent Env proteins that could explain the stability of cluster formation. We present an updated HIV-1 model and postulate novel roles of the MA shell and Env structure.

The latest anatomical discovery: the parathyroid glands or Glandulae parathyreoideae of Owen-Sandström-Gley.

In 1852, Owen, a prominent British anatomist, described the parathyroid glands. While dissecting a rhinoceros, he noted a small compact yellow body, attached to the thyroid. Virchow and later Remak described the human parathyroids around 1960, but credit for the first complete description goes to the Sandström in 1980. More than a decade later Gley, showed that it was the removal of the parathyroids that accounted for the tetany that followed thyroidectomy. The association of parathyroid pathology and skeletal abnormalities was made in 1914 by Erdheim and Schlagenhaufer, and Mandl, was the first surgeon to successfully treat a case of osteitis fibrosa by surgical removal of a parathyroid adenoma in 1925. The most extensive work on hyperparathyroidism was done in the 1930s by Albright form Boston, who described parathyroid hyperplasia, and differentiated between primary, secondary and tertiary hyperparathyroidism. Progresses in anatomy, physiology and surgery of the parathyroid glands, have contributed to various effective modalities of diagnosis and treatment.

En 1852, Owen, un destacado anatomista británico, describió las glándulas paratiroides. Mientras realizaba la disección de un rinoceronte indio, observó un pequeño cuerpo amarillo compacto, unido a la tiroides. Virchow, y más tarde Remak, describieron las paratiroides humanas alrededor de 1860, pero el crédito por la primera descripción completa es para Sandström en 1880. Más de una década después, Gley demostró que era la eliminación de las paratiroides lo que explicaba la tetania después de la tiroidectomía. La asociación de la patología paratiroidea y las anomalías esqueléticas fue establecida en 1914 por Erdheim y Schlagenhaufer, y Mandl fue el primer cirujano en tratar con éxito un caso de osteítis fibrosa mediante la extirpación quirúrgica de un adenoma paratiroideo en 1925. El trabajo más extenso sobre el hiperparatiroidismo fue realizado en la década de 1930 por Albright, en Boston, quien describió la hiperplasia paratiroidea y la diferenció del hiperparatiroidismo primario, secundario y terciario. Los avances en anatomía, fisiología y cirugía de las glándulas paratiroides han contribuido a diversas modalidades efectivas de diagnóstico y tratamiento.

Immunohistochemistry in Historical Perspective: Knowing the Past to Understand the Present.

Immunohistochemistry is an extraordinary and extensively used technique whereby antibodies are used to detect antigens in cells within a tissue section. It has numerous applications in medicine, particularly in cancer diagnosis. It was Albert Hewett Coons, Hugh J Creech, Norman Jones, and Ernst Berliner who conceptualized and first implemented the procedure of immunofluorescence in 1941. They used fluorescein isothiocyanate (FITC)-labelled antibodies to localize pneumococcal antigens in infected tissues. Since then, with improvement and development of protein conjugation, enzyme labels have been introduced, such as peroxidase and alkaline phosphatase. The history of immunohistochemistry (IHC) combines physiology, immunology, biochemistry, and the work of various Nobel Prize laureates. From von Behring who was awarded de first Nobel Prize in 1901 for his work on serum therapy to the 1984 Nobel Prize for the discovery of monoclonal antibodies by Milstein, Kohler, and Jerne, IHC is a story of cooperation and collaboration which led to the development of this magnificent technique that is used daily in anatomical pathology laboratories worldwide.

ALK-Negative Anaplastic Large Cell Lymphoma: Current Concepts and Molecular Pathogenesis of a Heterogeneous Group of Large T-Cell Lymphomas.

Anaplastic large cell lymphoma (ALCL) is a subtype of CD30+ large T-cell lymphoma (TCL) that comprises ~2% of all adult non-Hodgkin lymphomas. Based on the presence/absence of the rearrangement and expression of anaplastic lymphoma kinase (ALK), ALCL is divided into ALK+ and ALK-, and both differ clinically and prognostically. This review focuses on the historical points, clinical features, histopathology, differential diagnosis, and relevant cytogenetic and molecular alterations of ALK- ALCL and its subtypes: systemic, primary cutaneous (pc-ALCL), and breast implant-associated (BIA-ALCL). Recent studies have identified recurrent genetic alterations in this TCL. In systemic ALK- ALCL, rearrangements in DUSP22 and TP63 are detected in 30% and 8% of cases, respectively, while the remaining cases are negative for these rearrangements. A similar distribution of these rearrangements is seen in pc-ALCL, whereas none have been detected in BIA-ALCL. Additionally, systemic ALK- ALCL-apart from DUSP22-rearranged cases-harbors JAK1 and/or STAT3 mutations that result in the activation of the JAK/STAT signaling pathway. The JAK1/3 and STAT3 mutations have also been identified in BIA-ALCL but not in pc-ALCL. Although the pathogenesis of these alterations is not fully understood, most of them have prognostic value and open the door to the use of potential targeted therapies for this subtype of TCL.

Breast implant-associated anaplastic large cell lymphoma: clinical follow-up and analysis of sequential pathologic specimens of untreated patients shows persistent or progressive disease.

Breast implant-associated anaplastic large cell lymphoma (ALCL) is a distinctive type of T-cell lymphoma that arises around textured-surface breast implants. In a subset of patients, this disease can involve surrounding tissues, spread to regional lymph nodes, and rarely metastasize to distant sites. The aim of this study was to assess sequential pathologic specimens from patients with breast implant-associated ALCL to better understand the natural history of early-stage disease. To achieve this goal, we searched our files for patients who had breast implant-associated ALCL and who had undergone earlier surgical intervention with assessment of biopsy or cytologic specimens. We then focused on the patient subset in whom a definitive diagnosis was not established, and patients did not receive current standard-of-care therapy at that time. We identified a study group of ten patients with breast implant-associated ALCL in whom pathologic specimens were collected 0.5 to 4 years before a definitive diagnosis was established. A comparison of these serial biopsy specimens showed persistent disease without change in pathologic stage in three patients, progression in five patients, and persistence versus progression in two patients. Eventually, six patients underwent implant removal with complete capsulectomy and four underwent partial capsulectomy. Seven patients also received chemotherapy because of invasive disease, three of whom also received radiation therapy, two brentuximab vedotin after chemotherapy failure, and one allogeneic stem cell transplant. Eight patients achieved complete remission and two had partial remission after definitive therapy. At time of last follow-up, six patients were alive without disease, one had evidence of disease, one died of disease, and two patients died of unrelated cancers. In summary, this analysis of sequential specimens from patients with breast implant-associated ALCL suggests these neoplasms persist or progress over time if not treated with standard-of-care therapy.

Management of Residual Disease After First-line Chemotherapy in a Patient With a Nonseminomatous Germ Cell Tumor.

The case An 18-year-old male presented with a one-month history of a nonpainful right testicular enlargement. He had no family history of neoplasia, nor any relevant past medical history. The physical examination was only remarkable for an enlarged right testicle. A testicular ultrasound revealed a 2.5-cm tumor, and serum tumor markers revealed an elevated ß-human chorionic gonadotropin (ß-HCG), 22 mUI/L (normal, < 0.06 mUI/L); elevated alpha-fetoprotein (AFP), 329 ng/mL (normal, 0-9 ng/mL); and normal lactate dehydrogenase (LDH), 135 /L (normal, 179 U/L). A right radical inguinal orchiectomy was performed. Pathological examination revealed a 2.4 cm by 2 cm embryonal carcinoma with tumor invasion into the tunica albuginea. Postsurgical tumor markers obtained 3 weeks after orchiectomy were ß-hCG, 100.5 mUI/L (normal, < 0.06 mUI/L); AFP, 1075 ng/mL (normal, 0-9 ng/mL); and LDH, 180 U/L (normal, 179 U/L). A chest, abdomen, and pelvis CT scan showed a 2.7-cm retroperitoneal lymph node enlargement, without visceral metastasis. Given the presence of node-positive disease with S2 serum markers, the diagnosis of a stage IIIB intermediate risk nonseminomatous germ cell tumor (NSGCT) was determined, and the patient underwent sperm banking. The patient was started on chemotherapy with 4 cycles of BEP (bleomycin, etoposide, and cisplatin), with a favorable tumor marker decline according to the Gustave-Roussy nomogram. After completion of the fourth chemotherapy cycle, serum tumor markers were negative, and 8 weeks after chemotherapy, the follow-up CT showed a 1.6-cm residual retroperitoneal lymph node conglomerate.

Carl von Rokitansky, el Linneo de la anatomía patológica / Carl von Rokitansky, the Linné of pathological anatomy

Resumen Carl von Rokitansky fue una de las figuras más importantes en la anatomía patológica y el responsable, en parte, del renacimiento de Viena como centro de la medicina a mediados del siglo XIX. Nació en la actual Hradec Králové, estudió medicina en Praga y Viena y se graduó en 1828. Tuvo gran influencia de los estudios de anatomía, embriología y patología de Andral, Lobstein y Meckel. En la escuela de Viena fue asistente de anatomía patológica de Johann Wagner y se convirtió en profesor de anatomía patológica, donde permaneció hasta cuatro años antes de su muerte. Rokitansky hizo énfasis en correlacionar la sintomatología del enfermo con los cambios post mortem. Es posible que haya tenido acceso a entre 1500 y 1800 cadáveres al año para que pudiera realizar 30 000 necropsias; además, revisó varios miles más de autopsias. En Handbuch der Pathologischen Anatomie, publicado entre 1842 y 1846, realizó numerosas descripciones: de la neumonía lobular y lobular, endocarditis, enfermedades de las arterias, quistes en varias vísceras, diversas neoplasias y de la atrofia aguda amarilla del hígado. Con su brillante labor de patología macroscópica, Rokitansky estableció la clasificación nosológica de las enfermedades, por lo cual Virchow lo llamó “el Linneo de la anatomía patológica”.

Abstract Carl von Rokitansky was one of the most important figures in pathological anatomy, and was largely responsible for the resurgence of Vienna as the great medical center of the world in the mid-19th century. He was born in current Hradec Králové, studied medicine in Prague and Vienna and was graduated in 1828. He was greatly influenced by the anatomy, embryology and pathology studies of Andral, Lobstein and Meckel. At the Vienna School, he was Johann Wagner pathological anatomy assistant and became a pathology professor, where he remained until four years before his death. Rokitansky emphasized the importance of correlating patient symptoms with postmortem changes. It is possible that he had access to between 1,500 and 1,800 cadavers annually to be able to perform 30,000 necropsies; in addition, he reviewed several thousand more autopsies. In Handbuch der pathologischen Anatomie, published between 1842 and 1846, he made numerous descriptions: lobar and lobular pneumonia, endocarditis, diseases of the arteries, cysts in several viscera, various neoplasms and acute yellow atrophy of the liver. With his brilliant work on gross pathology, Rokitansky established the nosological classification of diseases, for which Virchow named him “the Linné of pathological anatomy”.

Carl von Rokitansky, the Linné of pathological anatomy.

Carl von Rokitansky was one of the most important figures in pathological anatomy, and was largely responsible for the resurgence of Vienna as the great medical center of the world in the mid-19th century. He was born in current Hradec Králové, studied medicine in Prague and Vienna and was graduated in 1828. He was greatly influenced by the anatomy, embryology and pathology studies of Andral, Lobstein and Meckel. At the Vienna School, he was Johann Wagner pathological anatomy assistant and became a pathology professor, where he remained until four years before his death. Rokitansky emphasized the importance of correlating patient symptoms with postmortem changes. It is possible that he had access to between 1,500 and 1,800 cadavers annually to be able to perform 30,000 necropsies; in addition, he reviewed several thousand more autopsies. In Handbuch der pathologischen Anatomie, published between 1842 and 1846, he made numerous descriptions: lobar and lobular pneumonia, endocarditis, diseases of the arteries, cysts in several viscera, various neoplasms and acute yellow atrophy of the liver. With his brilliant work on gross pathology, Rokitansky established the nosological classification of diseases, for which Virchow named him "the Lineé of pathological anatomy".Carl von Rokitansky fue una de las figuras más importantes en la anatomía patológica y el responsable, en parte, del renacimiento de Viena como centro de la medicina a mediados del siglo XIX. Nació en la actual Hradec Králové, estudió medicina en Praga y Viena y se graduó en 1828. Tuvo gran influencia de los estudios de anatomía, embriología y patología de Andral, Lobstein y Meckel. En la escuela de Viena fue asistente de anatomía patológica de Johann Wagner y se convirtió en profesor de anatomía patológica, donde permaneció hasta cuatro años antes de su muerte. Rokitansky hizo énfasis en correlacionar la sintomatología del enfermo con los cambios post mortem. Es posible que haya tenido acceso a entre 1500 y 1800 cadáveres al año para que pudiera realizar 30 000 necropsias; además, revisó varios miles más de autopsias. En Handbuch der Pathologischen Anatomie, publicado entre 1842 y 1846, realizó numerosas descripciones: de la neumonía lobular y lobular, endocarditis, enfermedades de las arterias, quistes en varias vísceras, diversas neoplasias y de la atrofia aguda amarilla del hígado. Con su brillante labor de patología macroscópica, Rokitansky estableció la clasificación nosológica de las enfermedades, por lo cual Virchow lo llamó "el Linneo de la anatomía patológica".

[The histological and immunohistochemical diagnosis of solid pseudopapillary neoplasm of the pancreas and its differential diagnosis]. / El diagnóstico histológico e inmunohistoquímico de la neoplasia sólida pseudopapilar de páncreas y su diagnóstico diferencial.

Solid pseudopapillary neoplasm of the pancreas is a rare tumor of uncertain histogenesis, described separately by Gruber and Frantz, that accounts for between approximately 1% and 3% of pancreatic neoplasms. It is characterized by a cystic and solid pattern of growth patterns with formation of pseudopapillae. It occurs primarily in young women, although cases in children and older patients and men have been reported. The tumor is of low-grade malignant potential, as the majority of the cases are cured by simple but complete surgical resection. Knowledge of the unique morphologic characteristics of this neoplasm is essential for the correct diagnosis. We review herein the pathologic and immunohistochemical features of this neoplasm and its differential diagnosis with other pancreatic tumors.

Discriminant analysis and machine learning approach for evaluating and improving the performance of immunohistochemical algorithms for COO classification of DLBCL.

BACKGROUND: Diffuse large B-cell lymphoma (DLBCL) is classified into germinal center-like (GCB) and non-germinal center-like (non-GCB) cell-of-origin groups, entities driven by different oncogenic pathways with different clinical outcomes. DLBCL classification by immunohistochemistry (IHC)-based decision tree algorithms is a simpler reported technique than gene expression profiling (GEP). There is a significant discrepancy between IHC-decision tree algorithms when they are compared to GEP. METHODS: To address these inconsistencies, we applied the machine learning approach considering the same combinations of antibodies as in IHC-decision tree algorithms. Immunohistochemistry data from a public DLBCL database was used to perform comparisons among IHC-decision tree algorithms, and the machine learning structures based on Bayesian, Bayesian simple, Naïve Bayesian, artificial neural networks, and support vector machine to show the best diagnostic model. We implemented the linear discriminant analysis over the complete database, detecting a higher influence of BCL6 antibody for GCB classification and MUM1 for non-GCB classification. RESULTS: The classifier with the highest metrics was the four antibody-based Perfecto-Villela (PV) algorithm with 0.94 accuracy, 0.93 specificity, and 0.95 sensitivity, with a perfect agreement with GEP (κ = 0.88, P < 0.001). After training, a sample of 49 Mexican-mestizo DLBCL patient data was classified by COO for the first time in a testing trial. CONCLUSIONS: Harnessing all the available immunohistochemical data without reliance on the order of examination or cut-off value, we conclude that our PV machine learning algorithm outperforms Hans and other IHC-decision tree algorithms currently in use and represents an affordable and time-saving alternative for DLBCL cell-of-origin identification.

Infantile systemic juvenile xanthogranuloma case with massive liver infiltration.

Infantile systemic juvenile xanthogranuloma (ISJXG) is an uncommon form of juvenile xanthogranuloma, a non-Langerhans cell proliferation of infancy and early childhood. In a small percentage of patients, the visceral involvement-most commonly to the central nervous system, liver, spleen, or lungs-may be associated with severe morbidity, and eventually fatal outcome. Here we describe the clinical and pathological findings of a 28-day-old girl with ISJXG who died with respiratory distress syndrome. She had few cutaneous lesions but massive liver and spleen infiltration; other affected organs were multiple lymph nodes, thoracic parasympathetic nodule, pleura, pancreas, and kidneys. Additional findings were mild pulmonary hypoplasia and bacteremia. Immunohistochemistry on fixed tissues is the standard for diagnosis. Immunophenotype cells express CD14, CD68, CD163, Factor XIIIa, Stabilin-1, and fascin; S100 was positive in less than 20% of the cases; CD1a and langerin were negative. No consistent cytogenetic or molecular genetic defect has been identified. This case demonstrates that the autopsy is a handy tool, because hepatic infiltration, which was not considered clinically, determined a restrictive respiratory impairment. In our opinion, this was the direct cause of death.

Infantile systemic juvenile xanthogranuloma case with massive liver infiltration

Infantile systemic juvenile xanthogranuloma (ISJXG) is an uncommon form of juvenile xanthogranuloma, a non-Langerhans cell proliferation of infancy and early childhood. In a small percentage of patients, the visceral involvement­most commonly to the central nervous system, liver, spleen, or lungs­may be associated with severe morbidity, and eventually fatal outcome. Here we describe the clinical and pathological findings of a 28-day-old girl with ISJXG who died with respiratory distress syndrome. She had few cutaneous lesions but massive liver and spleen infiltration; other affected organs were multiple lymph nodes, thoracic parasympathetic nodule, pleura, pancreas, and kidneys. Additional findings were mild pulmonary hypoplasia and bacteremia. Immunohistochemistry on fixed tissues is the standard for diagnosis. Immunophenotype cells express CD14, CD68, CD163, Factor XIIIa, Stabilin-1, and fascin; S100 was positive in less than 20% of the cases; CD1a and langerin were negative. No consistent cytogenetic or molecular genetic defect has been identified. This case demonstrates that the autopsy is a handy tool, because hepatic infiltration, which was not considered clinically, determined a restrictive respiratory impairment. In our opinion, this was the direct cause of death.

Hematoxylin: Mesoamerica's Gift to Histopathology. Palo de Campeche (Logwood Tree), Pirates' Most Desired Treasure, and Irreplaceable Tissue Stain.

Hematoxylin is a basic dye derived from the heartwood of Palo de Campeche ( Haematoxylum campechianum), the logwood tree native to Mexico and Central America. Haematoxylum means "bloodwood" in reference to its dark-red heartwood and campechianum refers to its site of origin, the coastal city of Campeche on the Yucatan Peninsula, Mexico. Hematoxylin is colorless but it turns into the color dye hematein after oxidation (ripening). The dyeing property of logwood was well-known to the natives of the Yucatan Peninsula before the arrival of the Spaniards who brought it to Europe shortly after the discovery of the Americas. An important trade soon developed related to growing and preparing hematoxylin for dyeing fabrics. Pirates discovered that one shipload of logwood was equivalent to a year's value from any other cargo, and by 1563, more than 400 pirate vessels wandered the Atlantic Ocean and attacked Spanish galleons transporting gold, silver, and logwood from the Americas to Europe. Hematoxylin and eosin is a staining method that dates back to the late 19th century. In 1865 and 1891, Böhmer and Meyer, respectively, first used hematoxylin in combination with a mordant (alum). Later, with the use of anilines by Ehrlich, the repertoire of stains expanded rapidly resulting in the microscopic descriptions of multiple diseases that were defined by their stainable features. Today hematoxylin, along with eosin, remains the most popular stain in histology.

[The histopathology and immunohistochemistry of granular cell tumour. A study of 12 cases with a brief historical note]. / Análisis histopatológico e inmunohistoquímico del tumor de células granulares. Estudios de 12 casos con una breve nota histórica.

INTRODUCTION AND OBJECTIVE: Granular cell tumour (GCT) is a benign neoplasm of neural/schwannian origin, usually presenting as a single asymptomatic lesion, mainly located in the dermis and subcutaneous tissue or submucosa, although multiple tumours may occur. Microscopically, GCTs are composed of large cells with abundant eosinophilic, granular cytoplasm arranged in sheets, nests, cords or trabeculae. Based on the cytological characteristics and the presence of necrosis, three types are recognized: benign, atypical and malignant. We aim to present the cytological and immunohistochemical characteristics of 12 granular cell tumours. MATERIALS AND METHODS: 12 cases of GCT were selected from the consultation files of one of the authors (COH) The paraffin embedded tissue was processed for immunostaining with S-100 protein, calretinin, CD68, α-inhibin, PGP9.5, CD57 (Leu7), CD63 (NKI / C3), Gap43 (growth-associated protein-43), SOX10, TFE-3 and Ki-67. RESULTS AND CONCLUSIONS: 6 male and 6 female patients, with an average age of 40, made up the study group. The most frequent location for the tumours was in the subcutaneous soft tissues of the arms. There were no malignant cases. All tumours were positive for S-100, CD57, SOX10, calretinin, CD68, PGP9.5, α-inhibin and TFE-3, with a low Ki-67 (1-5%). Additionally, we reported, for the first time, the positive immunoreaction to Gap43 (growth-associated protein-43) in GCT.

Myopericytoma in an unusual location.

Myopericytoma is a soft-tissue tumor of perivascular cells (pericytes). It is slow-growing, usually asymptomatic, and generally benign, although a malignant variant has been described. The etiology is unknown, but it has been associated with local trauma. The most common location is on the distal extremities. Histologically, it is characterized by a well-circumscribed, non-encapsulated proliferation of spindle shaped cells similar to myofibroblasts with oval nuclei and eosinophilic cytoplasm, arranged in perivascular concentric rings. There are few mitoses and no necrosis is reported. The immunohistochemical analysis is positive for smooth muscle actin and negative or weakly positive for desmin. A low Ki-67 proliferation index is typical. Treatment is surgical excision with free margins. Recurrences after adequate excision are uncommon. We describe a 48-year-old woman with a myopericytoma in an unusual location (next to the inner corner of her left eye) who was treated with surgical excision; there has been no recurrence after 5 years of follow up.

Approach to dermal-based lymphoid infiltrates and proliferations.

The histopathological diagnosis of dermal-based lymphoid infiltrates and proliferations is often challenging due to the vast list of biologically diverse entities that archetypally or occasionally center in the mid-dermis, especially because significant overlap exists in their clinical, histopathologic, and immunophenotypic features. The differential diagnosis includes reactive infiltrates in common and rare inflammatory dermatoses, benign conditions that may mimic lymphoid neoplasms (pseudolymphomas), and true clonal proliferations arising either primarily in the skin or rarely in extracutaneous tissues with secondary cutaneous dissemination. While numerous histopathological and immunophenotypic features have been reported to support a definitive diagnosis, no single ancillary test is sufficient for their distinction. Therefore, in this review we advocate a stepped histopathological approach for dermalbased lymphoid infiltrations, employing as key elements the general lymphocytic composition (relative B- versus T-cell ratio), coupled with the predominant cytomorphology (cell size) present. Following this strategy, the relative incidence of cutaneous involvement by each disease should always be considered, as well as the notion that a definitive diagnosis must be founded on a multiparameter approach integrating all clinical, histopathologic, immunophenotypic, and-in selected cases-molecular features.

Castleman disease. Histopathological and immunohistochemical analysis of 39 cases. / Enfermedad de Castleman. Análisis histopatológico e inmunohistoquímico de treinta y nueve casos.

Introduction: Castleman disease (CD) is a rare lymphoproliferative that comprises two distinct clinical subtypes (unicentric and multicentric) and has two basic histopathology patterns that are hyaline-vascular (HV) and plasma-cell (PC) type. Some cases of multicentric PC disease are associated with HHV-8 infection. Objective: To present the histopathologic and immunohistochemical characteristics of 39 cases of CD. Methods: A review of cases with the diagnosis CD from the files of the Department of Pathology of the ABC Medical Centre in Mexico City was performed. Thirty-nine cases of CD were identified, and a detailed paraffin immunophenotypic study of 9 of them was completed using desmin, cytokeratin OSCAR (CO) and Epidermal growth factor receptor (EGFR), to evaluate the dendritic cell population. Results and Conclusions: Of the 39 cases of CD, 24 were HV and 15 CP. All HV cases were unicentric and only one case of CP was multicentric. The most frequent localization in both subtypes was in lymph nodes; 21/24 cases in HV and 15 cases of CP. All cases were immunostained with CD20 that was expressed in the germinal centers (CGs), CD3 in the paracortical zone, and CD21 in follicular dendritic cells (CDF) within CGs, with expansion towards the area of the hyperplastic mantle zone (only in the HV variant). One case of CD CP was positive for HHV-8. Of the nine cases (6 HV and 3 PC cases) that were detailed with IHC, we found EGFR expression in FDC in all but one of the 9 cases studied and desmin was positive in fibroblastic reticulum cells (FRC) in all, but one of the cases of CD. CO was positive FRC in 3 of 6 cases of HV type and all (3) of the PC type. Clinical, histopathological and HIV and HHV-8 status markers, allow for the classification of CD into groups with markedly different outcomes and disease associations.