First description of a primary esophageal histiocytic sarcoma in a dog

An 11-year-old male Schnauzer dog was referred for investigation of cough and regurgitation of one month duration and gradual hyporexia for the previous five months. Complete blood count showed severe leukocytosis. On ventrodorsal and lateral thoracic radiographs a soft tissue mass was visible in the craniodorsal mediastinum. Endoscopy showed esophageal dilatation and an irregular, nodular, friable, exophytic mass in the thoracic esophagus, which was invasive, vascularized and had ulcerated areas. The mass occluded approximately 90% of the esophageal lumen. The mucosa in the orad portion of the thoracic esophagus was pale and the aborad portion was hyperemic (red) with hemorrhages. The mucosa of the cervical and abdominal esophagus was macroscopically unremarkeble. Multiple biopsies using endoscopic cup biopsy forceps were taken from the mass for histopathologic analysis and a percutaneous endoscopic gastrostomy was performed. Histopathologic analysis of the biopsy samples was inconclusive due to the marked necrosis. The poor clinical condition of the dog precluded a more invasive approach, and palliative and supportive treatment was continued. After 100 days of follow-up, clinical signs worsened, and that day the dog had a fatal cardiac arrest due to aspiration pneumonia and sepsis. Postmortem examination showed a multilobulated mass in the esophageal wall with infiltration into the overlying esophageal mucosa and pulmonary and renal metastases. Histological examination revealed a poorly differentiated sarcoma. On immunohistochemical examination, the neoplastic cells showed marked cytoplasmic staining for vimentin and Iba-1. The proliferative rate was approximately 30% by Ki-67. Histological and immunohistochemical examination revealed the esophageal mass to be a primary histiocytic sarcoma. Histiocytic sarcoma is an extremely rare primary esophageal neoplasm in humans, and so far, there is no description in dogs. To the best of the authors knowledge this is the first case of primary esophageal histiocytic sarcoma in dogs. The clinical information reported here should improve recognition and aid in diagnosis of future cases.

Immunohistochemical expression of vimentin, E-cadherin, and CD45 in natural cases of canine cutaneous round tumors

Round cell tumors are common cutaneous lesions in dogs, with increased occurrence percentages among different skin tumors. This study aimed to investigate the frequency as well as gross and pathological characteristics of round cell tumors in natural cases of tumorous dogs in relation to breed, sex, and age. Moreover, it aimed to evaluate the immunohistochemical expression of a panel of immunohistochemical stains, including vimentin, E-cadherin, and cluster of differentiation (CD45) as an adjunct technique for the differential diagnosis of cutaneous round cell neoplasm. Data were collected from 64 dogs of both sexes (36 females and 28 males), various breeds, and different ages (8 months to 7 years). The histopathological nature of neoplastic growth was reported, and neoplasm prevalence was classified using age, sex, breed, and site on the body. We observed 48 cases of transmissible venereal tumors, 12 cutaneous histiocytomas, and 4 histiocytic sarcoma. Immunohistochemical characterization revealed an intense positive immunoreactivity for vimentin in transmissible venereal tumor cells and moderate positive immunoreactivity for E-cadherin and CD45 in cutaneous histiocytoma and histiocytic sarcoma cells. In conclusion, the canine transmissible venereal tumor was the most frequent form of round cell tumor; thus, a definitive cutaneous neoplasm diagnosis should be based on histopathological morphology and immunohistochemical findings.

A rare case of primary central nervous system histiocytic sarcoma harboring a novel ARHGAP45::BRAF fusion: a case report and literature review

INTRODUCTION

Patients with histiocytic sarcoma occurring in the central nervous system (CNS) are rare and have a very poor prognosis. The increased use of molecular diagnostic approaches in solid tumors has brought more opportunities for the diagnosis and treatment of central nervous system histiocytic sarcoma (CNSHS).

CASE DESCRIPTION

A 9-year-old girl was admitted to the hospital with pain in her head and neck, as well as vomiting. Imaging scans showed a prominent abnormality in the anterior falciform region, and histopathology revealed the presence of CD68 (+) and CD163 (+) cells, leading to a preliminary diagnosis of primary intracerebral CNSHS. Molecular profiling tests identified a new variant of ARHGAP45::BRAF fusion in this case, which has not been reported in any other tumor. The patient underwent surgical removal of the tumor and will require long-term monitoring.

CONCLUSION

The presence of the BRAF point mutation, predominantly BRAF p.V600E, has been documented in prior literature of CNSHS. This is the first case of pediatric histiocytic sarcoma in the anterior falciform region who has a unique ARHGAP45::BRAF fusion. The findings of our study indicate that a broader range of molecular assays should be employed in the diagnosis of CNSHS and opens up new possibilities for the treatment of the patient.

Histiocytic sarcoma in renal transplant patients: a literature review

BACKGROUND

Histiocytic sarcoma (HS) is defined as neoplasm resembling morphological and immunophenotypic characteristics of mature histiocytes. It is a rare form of lymphoid neoplasms. Despite advances in treatment and diagnosis of histiocytic sarcoma, majority of cases had poor prognosis due to progressive nature of the disease. In the following article, all reported cases of histiocytic sarcoma in renal transplant patients are reviewed.

METHODS

In our literature review, all relevant reports were collected electronically by entering the necessary keywords. A Boolean approach using Medical Subject Heading (MeSH) keywords was implemented. After establishing the inclusion/exclusion criteria, article titles and abstracts were evaluated by Systematic Reviews and Meta-Analyses (PRISMA) standards for 2020. All cases of histiocytic sarcoma in renal transplant patients were included.

RESULT

Based on our inclusion and exclusion criteria 4 case reports were yielded in this review. Two were males and 2 were females with the mean age of 42.25 years. Fever was the most common symptom. Although tumor originated from the native kidney on one patient, the site of the primary tumor was thorax, oropharynx, and transplanted kidney in the rest. Metastasis was detected in all cases. Prednisone was used for all cases. EBV was positive in 2 cases and negative in one of them. Histology was diagnostic and similar in all cases. Immunohistochemistry was done for 3 cases. Although chemotherapy was done for 3 patients, all 4 cases ended in mortality.

CONCLUSION

Despite the fact that neoplasms are post renal transplant complications, histiocytic sarcoma is a scarce and fatal entity in such patients. Histological and immunohistochemistry tests are the corner stone in diagnosis of histiocytic sarcoma.

[Pulmonary histiocytic sarcoma]

Histiocytic sarcoma is an uncommon hematological malignancy. Its occurrence in the lung is very rare. Due to the small number of cases and the clinical and pathological features of the disease, the diagnosis can be challenging. Its optimal treatment is not yet known, in locally confined cases - depending on the location and size - surgical removal is part of complex oncotherapy. We report the case of a 52-year-old man with a tumor of central localization in the left lung. Pulmonectomy was performed. Histology verified histiocytic sarcoma of the lung. An overview of clinical features of the entity is presented in connection with our case report. Orv Heti. 2023; 164(34): 1350-1357.

The many faces of mouse histiocytic sarcoma in C57BL/6J mice

Histiocytic sarcoma is a tumor of the hematopoietic system considered to be derived from macrophages. Although rare in humans, it occurs frequently in mice. Histiocytic sarcoma can be a difficult tumor to diagnose due to its diverse cellular morphologies, growth patterns, and organ distributions. The varying morphology of histiocytic sarcomas makes it easy to confuse them with other types of neoplasia, including hepatic hemangiosarcoma, uterine schwannoma, leiomyosarcoma, uterine stromal cell tumor, intramedullary osteosarcoma, and myeloid leukemia. As such, immunohistochemistry (IHC) is often needed to differentiate histiocytic sarcomas from other common tumors in mice that they can morphologically mimic. The goal of this article is to present a broader perspective of the diverse cellular morphologies, growth patterns, organ distributions, and IHC labeling of histiocytic sarcomas encountered by the authors. This article describes these features in a set of 62 mouse histiocytic sarcomas, including the IHC characterization of the tumors using a panel of markers for the macrophage antigens F4/80, IBA1, MAC2, CD163, CD68, and lysozyme, and describes differentiating features of histiocytic sarcomas from other morphologically similar tumors. The genetic changes underlying the pathogenesis of histiocytic sarcoma in humans are beginning to be elucidated, but this is difficult due to its rarity. The higher prevalence of this tumor in mice provides opportunities to investigate mechanisms of its development and to test potential treatments.

Case report: Targeting the PD-1 receptor and genetic mutations validated in primary histiocytic sarcoma with hemophagocytic lymphohistiocytosis

Histiocytic sarcoma (HS) is a rare hematological malignancy with limited treatment options, and it is also prone to complications such as hemophagocytic lymphohistiocytosis (HLH) in the later stages of the disease, leading to difficulties in treatment and poor prognosis. It highlights the importance of developing novel therapeutic agents. Herein, we present a case of a 45-year-old male patient who was diagnosed with PD-L1-positive HS with HLH. The patient was admitted to our hospital with recurrent high fever, multiple skin rashes with pruritus throughout the body and enlarged lymph nodes. Subsequently, pathological biopsy of the lymph nodes revealed high expression of CD163, CD68, S100, Lys and CD34 in the tumor cells and no expression of CD1a and CD207, confirming this rare clinical diagnosis. Concerning the low remission rate by conventional treatment in this disease, the patient was administered with sintilimab (an anti-programmed cell death 1 [anti-PD-1] monoclonal antibody) at 200 mg/d combined with a first-line chemotherapy regimen for one cycle. Further exploration of pathological biopsy by using next-generation gene sequencing led to the use of targeted therapy of chidamide. After one cycle of combination therapy (chidamide+sintilimab, abbreviated as CS), the patient achieved a favorable response. The patient showed remarkable improvement in the general symptoms and laboratory examination results (e.g., elevated indicators of inflammation); even the clinical benefits was not persistent, he survived one more month after his cessation of treatment by himself due to economic difficulty. Our case suggests that PD-1 inhibitor coupled with targeted therapy might constitute a potential therapeutic option for primary HS with HLH.

Histiocytic sarcoma with spinal necrosis in a dog with progressing non-ambulatory tetraparesis

Background: Histiocytic sarcoma (HS) is an aggressive malignant neoplasm, and widespread metastasis occurs with a fatal outcome. HS involving the central nervous system is relatively uncommon. Spinal cord necrosis, a very rare condition, could be induced by ischemia or infarction. Here, we report a dog progressing non-ambulatory tetraparesis with spinal cord necrosis caused by HS. Case Description: A 9-year-old male Labrador retriever was presented with a progressing non-ambulatory tetraparesis. CT imaging revealed lysis of the spinous process of T7 and a ring-shaped lesion surrounding the soft tissue of lung fields. T2-weighted MRI showed the spinous processes of T6 to T8 as hyperintense, and the lesion infiltrated into the T7 vertebra and the spinal cord. After euthanasia, the final diagnosis upon necropsy was HS, which was observed in the lung, spinous process, thoracic cord, and the pulmonary hilar lymph node. Moreover, necrotic spots were spread widely through the thoracic spinal cord. Conclusion: This report outlines a case of canine HS in the lung, spinous process, thoracic cord, and pulmonary hilar lymph node. Ischemic deficit and necrosis of the thoracic spinal cord resulted from the compression of perivascular tumor cells, which rapidly led to progressive tetraparesis. Although the diagnosis was difficult, MRI and CT images helped determine the prognosis. To our knowledge, this is the first case report of canine HS with direct spinal cord involvement associated with spinal necrosis.

Primary Histiocytic Sarcoma of Brain-Illustration of Two Cases with Varied Histomorphological Features

Histiocytic sarcoma (HS) is an aggressive hematolymphoid malignancy that arises from non Langerhans histiocytes and usually involves the skin, lymph nodes, and intestine. The involvement of the central nervous system (CNS) is a rare occurrence with around 30 cases being reported in English literature. Morphological and immunohistochemical evidence of histiocytic differentiation is essential for diagnosis. Prognosis is very poor and consensus on treatment is not available mainly due to its rarity. We report two cases of HS with varied clinical presentation and pathological findings and elucidate the diagnostic challenges of this rare entity.

Histiocytic Sarcoma with Invasive Urothelial Carcinoma of Urinary Bladder

We report a rare case of histiocytic sarcoma in association with invasive urothelial carcinoma involving the urinary bladder. A 67-year male patient, who presented with a complaint of macroscopic hematuria, was found to have a mass on urinary system ultrasonography. Abdominal magnetic resonance imaging was performed to evaluate the mass, which showed a 52×24 mm mass on the posterior wall of the bladder. The cystoscopic examination revealed two suspicious areas in close proximity to one another with solid-papillary character. The tissue samples were collected by means of transurethral resection. The evaluation of these samples revealed two distinct neoplastic patterns. The areas of invasive urothelial carcinoma infiltrating lamina propria were noted on the surface in addition to diffuse sheets of large cells with hyperchromatic nuclei and ample clear cytoplasm, with a patternless pattern among small lymphocytes in myxoid background in the lamina propria. The positive reactions were observed in these areas with CD45, fascin, and CD68, a histiocytic marker. The histopathological diagnosis was histiocytic sarcoma in combination with invasive urothelial carcinoma. Histiocytic sarcoma may mimic several other malignant lesions, and only immunohistochemistry can identify this tumour to allow correct treatment. We present this rare case to emphasise that this phenomenon should be considered in unusual tumors and sites. Key Words: Urinary bladder, Histiocytic sarcoma, Invasive urothelial carcinoma.

Successful Treatment of Incidental Histiocytic Sarcoma Concomitant with Laryngeal Carcinoma

Histiocytic sarcoma (HS) is an extremely rare non-Langerhans cell disorder with an aggressive course and limited treatment options. HS most often presents at an advanced clinical stage, with a limited response to chemotherapy and high mortality. No standard treatment has been established for HS. We herein describe the first case of HS concomitant with laryngeal carcinoma that was promptly diagnosed and successfully treated; the condition of the patient has remained stable for 4 years with no recurrence.

Leukemic Phase of Histiocytic Sarcoma of the Digestive System: A Rare Manifestation of a Rare Disease

Histiocytic sarcoma (HS) is a rare, malignant, and aggressive subtype of histiocytosis. We present an unusual case of aggressive HS presenting in the gastrointestinal tract and gallbladder that progressed after several lines of chemotherapy with a leukemic phase. We review the clinical, pathological, and molecular characteristics of HS in this case and review the literature on HS involving the digestive system as well as on overt leukemic phase of this disease. HS is often diagnosed at an advanced stage, and mortality is high. We discuss the therapeutic approach to patients with HS. We highlight the role of overexpression and somatic alterations in the RAF-MEK-ERK pathway in the pathogenesis of HS and discuss potential targeted approaches to treat these rare tumors.

Histiocytic Sarcoma

Histiocytic sarcoma (HS) is a rare hematopoietic malignancy originating from the monocyte/macrophage bone marrow lineage. HS can occur in isolation or in association with other hematological neoplasms such as non-Hodgkin lymphoma (NHL), myelodysplasia, or acute leukemia. Clinically, HS can affect lymph nodes, gastrointestinal tract, skin, bone marrow, and spleen as well as the central nervous system. Most cases of HS follow an aggressive clinical course, with most patients dying of progressive disease within one year of diagnosis.

Primary central nervous system histiocytic sarcoma: A case report and review of literature

RATIONALE

Primary central nervous system histiocytic sarcoma (PCNSHS) is a rare lymphohematopoietic tumor with a histiocytic cell origin. To our knowledge, only 28 cases have been published in English and 2 cases in Chinese.

PATIENT CONCERNS

A 49-year-old Asian female presented to the hospital with a 2 month history of hypomnesia, odynophagia, and gait disorder. Physical examination demonstrated decreased lower extremity muscle strength. The patient denied a history of malignancy.

DIAGNOSES

Radiology demonstrated a lesion in parietal lobe with uniformenhancement. Histologic analysis showed pleomorphic tumor cells with a loose arrangement, effacing the normal brain tissue. The tumor cells exhibited abundant eosinophilic cytoplasm, highly atypical nuclei and predominant nucleoli. Immunohistochemistry revealed positive immunoreactivity for CD45, lysozyme, CD68, and CD163, and negative for pan-cytokeratin (CK), epithelial membrane antigen (EMA), glial fibrillary acidic protein (GFAP), CD3, CD20, CD1a, CD79a, CD138, oligodendrocyte transcription factor (olig2), CD15, melan-A, CD30, CD21, CD35, Human Melanoma Black-45 (HMB45), and anaplastic lymphoma kinase-1 (ALK-1). The diagnosis of PCNSHS was rendered.

INTERVENTIONS

The patient underwent complete surgical resection and adjuvant radiotherapy.

OUTCOMES

Follow-up information shows the patient died 8 months following the initial diagnosis.

LESSONS

PCNSHS is extremely rare with an aggressive clinical course. Immunohistiochemistry is necessary to make this diagnosis and to exclude other primary intracranial and lymphohematopoietic tumors. Further research is required to improve the outcome of patients with PCNSHS.

Histiocytic Sarcoma with p16-Overexpression Presenting as Uterine Cervical Mass

A 67-year-old woman presented with post-menopausal bleeding. Physical examination and imaging revealed a cervical mass with extensive pelvic involvement and supraclavicular lymphadenopathy. Clinical diagnosis was stage IVB cervical carcinoma. Cervical biopsy revealed high-grade squamous intraepithelial lesion and epithelioid tumor cells in the stroma. Lymph node biopsy revealed metastasis by similar epithelioid tumor cells. The epithelioid tumor cells were positive for p16, CD68, and CD163 on immunohistochemical study. The diagnosis of histiocytic sarcoma (HS) was rendered. This case demonstrated a rare presentation of HS mimicking cervical carcinoma. Awareness of this rare entity with appropriate ancillary tests is essential for accurate diagnosis. In contrast to the previous postulation of p16-inactivation as the pathogenesis of HS, p16-overexpression might suggest a different pathway for tumorigenesis.

Retroperitoneal Bulky Histiocytic Sarcoma Successfully Treated with Induction Chemotherapy Followed by Curative Surgery

Histiocytic sarcoma (HS) is a rare hematopoietic neoplasm. We report a patient with HS treated with induction chemotherapy followed by curative surgery. A 50-year-old man was referred to our hospital because of a retroperitoneal tumor. A computed tomography scan revealed a bulky retroperitoneal mass, infiltrating the surrounding organ. An excisional biopsy confirmed the diagnosis of HS. The tumor shrunk after multidrug chemotherapy. However, positron emission tomography showed uptake of fludeoxyglucose in the residual tumor. He underwent right nephrectomy to remove the tumor. Pathological examination showed complete response. Surgery combined with induction chemotherapy may be an effective way to manage HS.

Primary histiocytic sarcoma of the uterine cervix: an extremely rare entity

OBJECTIVE

Histiocytic sarcoma (HS) is an extraordinary rare tumor and it has an offensive clinical course. HS of the uterine cervix is a far uncommon tumor with just a few cases described so far. Here we presented a case of primary HS of the uterine cervix in a 62-year-old female initially misdiagnosed as large cell non-keratinizing squamous cell carcinoma. To the best of our knowledge, this is the first reported case of HS of the uterine cervix from Iran.

CASE REPORT

The patient presented with post-menopausal vaginal bleeding. Further evaluations revealed the presence of a relatively large cervical mass that was sampled. Under the preliminary diagnosis of large cell non-keratinizing squamous cell carcinoma, the patient underwent radical surgery. Postoperative pathological examination confirmed the diagnosis of HS of the uterine cervix. The patient received chemotherapy.

CONCLUSION

Clinical presentations of HS of the uterine cervix are very similar to more common cervical tumors; as a result its diagnosis relies on immunohistochemical methods. A correct diagnose could lead to the proper and timely treatment.

UNUSUAL CLINICAL CASES THAT MIMIC ACUTE DISSEMINATED ENCEPHALOMYELITIS

Acute disseminated encephalomyelitis (ADEM) is an immune-mediated monophasic inflammatory demyelinating disorder of the central nervous system which poses a diagnostic challenge. We report on six cases of different etiologies that mimicked the clinical and radiologic findings of ADEM. The cases were collected from four different reference hospitals in Turkey. The same radiologist from the Akdeniz University Faculty of Medicine examined the magnetic resonance images of all patients. Three (50%) patients had antecedent infections. Initial symptoms of the patients were as follows: fever in 50%, altered consciousness in 33.3% and convulsions in 16.7% of patients. Neurologic examination showed long tract signs in 83.3%, ataxia in 50% and altered consciousness in 50% of patients. Cerebrospinal fluid examination revealed lymphocytic pleocytosis only in case 6. Four patients received steroid pulse therapy and one of these initially underwent intravenous immunoglobulin therapy. The patients' definitive diagnoses were as follows: paraspinal neuroblastoma-associated paraneoplastic syndrome; histiocytic sarcoma; mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes; and cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy in one patient each, while two patients had hemophagocytic syndrome. The present case series demonstrated difficulties in diagnosing ADEM while revealing extremely rare disorders that mimic ADEM radiologically and clinically.

Suspected disseminated histiocytic sarcoma in a 3-year-old Perro de Presa Canario dog

A 3-year-old intact male Perro de Presa Canario dog was presented with acutely inflamed and edematous right hind limb, scrotum, prepuce, and an enlarged left carpus. Two weeks later the dog returned with weight loss, draining tracts in the right hind limb, dermal nodules, a palpable abdominal mass, and uveitis in the left eye. The dog succumbed to his illness 2 days later and a widely disseminated round cell tumor compatible with histiocytic sarcoma was diagnosed following postmortem examination.

Histiocytic sarcoma of the bile duct

An 80-year-old man was admitted with anorexia, a high fever and general icterus. Laboratory examinations revealed remarkable inflammation and elevation of liver/biliary enzymes. Computed tomography (CT) showed a high-density lesion in the bile duct, and endoscopic retrograde cholangiopancreatography (ERCP) disclosed an oval filling defect mimicking choledocholithiasis. Plastic stents were inserted to treat the acute cholangitis; however, the patient's symptoms recurred. An erythematous hypervascular mass obtained with a balloon catheter contained numerous pleomorphic histiocytic cells with eosinophilic cytoplasm, remarkable anisonucleosis and occasional mitoses. A diagnosis of histiocytic sarcoma (HS) was made based on the results of intensive immunohistochemistry. Monoclonal rearrangement of the IGH and TCRG genes, IGH split and IGH/BCL2 fusion was negative, although polysomy 8, 14, and 18 was detected. The patient was treated conservatively and died of the disease 20 months after the initial diagnosis. To the best of our knowledge, this is the first case of bile duct HS. This case, which involved numerical alterations of chromosomes, presented with CT and ERCP findings similar to those of choledocholithiasis.

[Histiocytic sarcoma]

Histiocytic sarcoma is a neoplasm arising from the histiocytes. Histiocytic neoplasms are among the rarest malignancies of lymphatic tissues. Occurs in less than 1% of all malignancies affecting lymph nodes and soft tissues [1,2]. The exact incidence of histiocytic sarcoma has not been described so far. In this article, we report three patients with HS, who were treated at the departement of Internal medicine, haematology and oncology, Faculty Hospital Brno. Despite the fact that all these patients had the same disease, the treatment effects differ depending on the stage of the disease at the time of diagnosis.

Unusual presentation of a rare cancer: histiocytic sarcoma in the brain 16 years after treatment for acute lymphoblastic leukemia

Histiocytic sarcoma (HS) is a very rare hematopoietic neoplasm that has been reported in association with other hematological malignancies. Presentation of HS in the central nervous system is even less common. Diagnosis of HS requires the presence of histiocytic markers and the systematic exclusion of markers of other cell lineages. Primary HS central nervous system tumors are aggressive and generally have poor outcomes. There are no standard treatment guidelines due to lack of clinical trials and a limited number of case reports. Here we present a unique case with two primary histiocytic lesions in the brain, refractory to systemic and radiation therapies, that developed after being treated for T-cell acute lymphoblastic leukemia 16 years prior.

[Unusual lung localization of histiocytic sarcoma]

Histiocytic sarcoma, proliferation araising from immunoregulatory effector system cells, is a very rare and recently recognised tumor. Diagnosis is based on immunohistochemistry and molecular genetic techniques, which allow to distinguish histiocytic sarcoma from lymphocytic proliferation, such as non-Hodgkin's. We report this rare case of multivisceral histiocytic sarcoma revealed by lung localization and for which the evolution was fatal.

Complete response of a patient with advanced primary splenic histiocytic sarcoma by treatment with chemotherapeutic drugs selected using the collagen gel droplet-embedded culture drug sensitivity test

A 69-year-old man presented with multiple nodules on the spleen and liver that had been detected by computed tomography (CT). A liver tumor biopsy was performed, and the patient was diagnosed to have histiocytic sarcoma (HS). Splenectomy was performed, and the chemosensitivity of the spleen tumor was measured using the collagen gel droplet-embedded culture drug sensitivity test (CD-DST). Hepatic arterial infusion chemotherapy was administered, based on the results of the CD-DST. The patient achieved complete remission (CR) after this therapy and remained alive without recurrence at the final follow-up. This is the first known case of CR in response to chemotherapy for advanced splenic HS.

[A rare cutaneous congenital sarcoma: plexiform fibrohistiocytic tumor]

We report the unusual case of a three-year-old girl which presented since birth a pigmented tumor of the left side 0.5cm in diameter. Surgical removal was decided given the hypothesis of a congenital naevo-cellular naevus. The histological study ended with the diagnosis of plexiform fibrohistiocytic tumor (PFHT). Two other congenital PFHT have been reported until now. PFHT is a rare mesenchymal neoplasm of intermediate malignancy, first reported by Enzinger and Zhang in 1988 which may be difficult to diagnose, because of its low frequency, particulary in congenital cases. It is important to distinguish it from others childhood cutaneous tumors (particulary plexiform neurofibroma, cellular neurothekeoma, infantile myofibromatosis, and fibrous hamartoma). The tumor has a high local recurrence rate and complete surgical resection of the tumor, with wider margins, is required.

Cytophagic histiocytic panniculitis with haemophagocytosis in a patient with familial multiple lipomatosis and review of the literature

We report a patient with the extremely rare familial multiple lipomatosis syndrome, who developed the uncommon autoimmune disease cytophagic histiocytic panniculitis, manifested as inflammation of preexisting lipomas. Despite his initial critical condition and unsuccessful treatment with steroids, he responded to cyclosporin and remains well 15 years after diagnosis. In contrast with most previous reports, our patient stays dependent on cyclosporin; repeated attempts of discontinuing or substituting treatment were quickly followed by relapse. Haemophagocytic panniculitis is considered as a T-cell disorder, but its exact pathophysiological mechanism has not been clarified. Differential diagnosis of cytophagic histiocytic panniculitis mainly includes malignant histiocytosis, subcutaneous panniculitis-like T-cell lymphoma (SPTCL) and lupus erythematosus panniculitis (lupus profundus). We discuss the main clinical features, diagnostic challenges and treatment issues of this usually benign, but at times life-threatening autoimmune condition.

A case of histiocytic sarcoma presenting with primary bone marrow involvement

Histiocytic sarcoma (HS) is a very rare neoplasm that often shows an aggressive clinical course and systemic symptoms, such as fever, weight loss, adenopathy, hepatosplenomegaly and pancytopenia. It may present as localized or disseminated disease. We describe here a 63-yr-old male who manifested systemic symptoms, including fever, weight loss and generalized weakness. Abdominal and chest computed tomography failed to show specific findings, but there was suspicion of multiple bony changes at the lumbar spine. Fusion whole body positron emission tomography, bone scan and lumbar spine magnetic resonance imaging showed multiple bone lesions, suggesting a malignancy involving the bone marrow (BM). Several BM and bone biopsies were inconclusive for diagnosis. Necropsy showed replacement of the BM by a diffuse proliferation of neoplastic cells with markedly increased cellularity (95%). The neoplastic cells were positive for lysozyme and CD68, but negative for T- and B-cell lineage markers, and megakaryocytic, epithelial, muscular and melanocytic markers. Morphologic findings also distinguished it from other dendritic cell neoplasms.

[A localised histocytic sarcoma in the stomach of a dog]

A 6-year-old neutered female Bernese mountain dog is described with anorexia, weight loss and melena. Gastric neoplasia was noticed (on ultrasound) and pathological examination ofgastric biopsies showed a histiocytic tumor. Necropsy confirmed the diagnosis of a localised histiocytic sarcoma. It was remarkable that the large tumor didn't lead to vomiting.

Histiocytic sarcoma: identification of its histiocytic origin using immunohistochemistry

We describe a 56-year-old woman with histiocytic sarcoma involving the bone marrow. The neoplastic cells proliferated diffusely and showed occasional erythrophagocytosis. Immunohistochemically, the neoplastic cells were positive for CD68, lysozyme, CD4 and CD163, but negative for B- and T-cell markers, S100 protein and epithelial markers. The patient received multi-agent chemotherapy and is living at 22 months after diagnosis without recurrence. Histiocytic sarcoma is an exceedingly rare hematopoietic neoplasm and the prognosis is poor due to its rapid progression, widespread disease and poor response to therapy. It is important to recognize this rare neoplasm and to confirm the diagnosis using specific immunohistochemical markers.

Malignant histiocytosis with central nervous system involvement and hepatic mucinous cystadenoma in a single patient with review of the literature

Malignant histiocytosis is a rare neoplasm of the reticuloendothelial system characterized by neoplastic proliferation of tissue histiocytes. We report a case of malignant histiocytosis in a 64-year-old female initially operated on for a mucinous cystadenoma of her liver. Four months after the operation, skin induration on the neck and anterior thoracic wall and systemic lymphadenopathy were noted. Histology and immunohistochemistry of the lymph node and bone marrow specimens showed extensive infiltration with atypical cells, resembling malignant histiocytes (CD45, CD45RO, CD11c, CD68, lysozyme, antitrypsin and alpha1-antichymotrypsin positive; CD1, CD35, B-cell and T-cells markers negative). She was treated with vinblastine, methotrexate and dexamethasone (3 cycles) without response. The therapy was switched to CHOP (cyclophosphamide, vincristine, doxorubicin, and prednisone) with disappearance of lymphadenopathy. Bone marrow infiltration by histiocytes was reduced to 20%. Two months after completion of 8 cycles of CHOP she experienced severe headaches, vomiting, loss of consciousness, and developed paraparesis. A CT scan of the brain was normal but the cerebrospinal fluid cytology showed presence of histiocytes. The patient was then treated with intrathecal methotrexate, prednisolone and cytosine-arabinoside and systemic chemotherapy with etoposide and cyclophosphamide. Her condition improved, she became conscious, her headache diminished, she became mobile but skin and nodal lesions reappeared along with extensive marrow histiocytic infiltration. She finally died 22 months after diagnosis.

A femorotibial joint swelling with popliteal lymph node enlargement in a Rottweiler

A 9-year-old male Rottweiler was presented to the Veterinary Medical Hospital Montenegro, Porto, Portugal with a large mass medial to the left stifle and radiographic signs of bone lysis involving the proximal tibia, fibula, and distal femur. A fine-needle aspiration was obtained from left popliteal lymph node, which was markedly enlarged. Cytologic examination revealed a highly cellular sample consisting of pleomorphic cells with marked anisocytosis and anisokaryosis and other criteria of malignancy. Some cells contained intracytoplasmic, granular, dark brown material, consistent with hemosiderin. Histologic evaluation of the surgically-excised lymph node revealed a neoplastic proliferation of histiocytic cells, with marked pleomorphism; occasional cells were erythrophagocytic. Mitotic figures were frequently observed, and many were atypical. Histologic findings were consistent with malignant histiocytosis. Necropsy examination confirmed the diagnosis of malignant histiocytosis with systemic involvement affecting most organs examined. This case of malignant histiocytosis case had an atypical clinical presentation, mimicking a musculoskeletal disorder. It underlines the importance of cytology as a simple, inexpensive, rapid and noninvasive complementary exam in routine clinical practice that can permit early diagnosis of the disease and timely selection of the most adequate therapy.

Cerebrospinal fluid from a 10-year-old dog with a single seizure episode

A cerebrospinal fluid sample collected from the cerebellomedullary cistern of a 10-year-old Shetland Sheepdog with a recent history of seizures was submitted for fluid analysis and cytologic examination. Key findings included a total nucleated cell count of 520/microL (reference interval 0-5 cells/microL), with a predominance of mononuclear cells, a protein concentration of 51.8 mg/dL (reference interval 0-35 mg/dL), and a glucose concentration of 44.7 mg/dL (reference interval 52-105 mg/dL). There was marked atypia of the mononuclear cells, with abundant eosinophilic cytoplasm, marked anisocytosis and anisokaryosis, occasional binucleated cells, mitotic figures, and rare erythrophagia. The cytologic interpretation was marked, monocytoid-rich, mixed cell pleocytosis with cellular atypia worrisome for neoplasia. In addition to histiocytic neoplasia, differentials included granulomatous meningoencephalomyelitis, necrotizing meningoencephalitis, and granulomatous inflammation. The dog did not respond to anti-inflammatory and anticonvulsive therapy. At necropsy, a mass involving the meninges and subtending the neuropil of the right temporal lobe of the cerebrum was found. Histologically, the mass was composed of large, bizarre histiocytic cells with multinucleated forms and numerous mitotic figures. Using immunochemistry on cytologic and histologic samples, the pleomorphic histiocytic cells were positive for CD1c, CD11ad, CD45, lysozyme, and vimentin, and were negative for CD3, CD4, CD79a, CD90, and pancytokeratin. These findings supported a diagnosis of primary CNS malignant histiocytosis of dendritic antigen-presenting cell (CD1c+) origin. To our knowledge, this is only the third reported case of primary CNS histiocytic sarcoma in dogs, and the first to demonstrate strong immunochemical evidence for dendritic antigen-presenting cell origin.

[Histiocytic sarcoma: a case report and review of the literature]

Histiocytic sarcoma is a rare neoplasm, and its aetiology is unknown. It is a malignant proliferation of neoplastic cells showing immunophenotypic and morphologic features similar to tissue histiocytes. The clinical course of histiocytic sarcoma is usually agressive. The signs and symptoms of histiocytic sarcoma are systemic symptoms (fever, weight loss), hepatosplenomegaly, adenopathies, intestinal obstruction, rash and pancytopenia. We present the case of a 75 years old woman, with fever, weight loss, anorexia, fatigue, splenomegaly and pancytopenia. Bone marrow examination showed the diagnosis of histiocytic sarcoma.