Mapping rRNA 2'-O-methylations and identification of C/D snoRNAs in Arabidopsis thaliana plants.

In all eukaryotic cells, the most abundant modification of ribosomal RNA (rRNA) is methylation at the ribose moiety (2'-O-methylation). Ribose methylation at specific rRNA sites is guided by small nucleolar RNAs (snoRNAs) of C/D-box type (C/D snoRNA) and achieved by the methyltransferase Fibrillarin (FIB). Here we used the Illumina-based RiboMethSeq approach for mapping rRNA 2'-O-methylation sites in A. thaliana Col-0 (WT) plants. This analysis detected novel C/D snoRNA-guided rRNA 2'-O-methylation positions and also some orphan sites without a matching C/D snoRNA. Furthermore, immunoprecipitation of Arabidopsis FIB2 identified and demonstrated expression of C/D snoRNAs corresponding to majority of mapped rRNA sites. On the other hand, we show that disruption of Arabidopsis Nucleolin 1 gene (NUC1), encoding a major nucleolar protein, decreases 2'-O-methylation at specific rRNA sites suggesting functional/structural interconnections of 2'-O-methylation with nucleolus organization and plant development. Finally, based on our findings and existent database sets, we introduce a new nomenclature system for C/D snoRNA in Arabidopsis plants.

Microcystic transitional cell carcinoma: a rare tumor of the urinary bladder.

Microcystic urothelial carcinoma is a rare variant of invasive transitional cell carcinoma recognized by the WHO classification. It is characterized by its deceptively benign appearance. The clinical course of this uncommon variety of carcinoma is not well known and their histological and immunohistological features are not well defined. We report a case of a 37-year-old man with a microcystic transitional cell carcinoma of the urinary bladder. He was diagnosed 4 years ago with cystitis glandularis lesions and nephrogenic adenoma. Through this observation we will try to define the clinical and pathological features of this uncommon tumor which must be differentiated from a number of proliferative lesions of the urothelium. The poor prognosis and aggressiveness of this tumor seems to be related to a higher stage and grade at diagnosis.

Relevant genetic polymorphisms and kidney expression of Toll-like receptor (TLR)-5 and TLR-9 in lupus nephritis.

Toll-like receptor (TLR) genetic polymorphisms may modify their expression causing inflammatory disorders and influencing both susceptibility and severity of lupus erythematosus. We aim to determine whether TLR-5 and TLR-9 gene polymorphisms are implicated in the susceptibility to systemic lupus erythematosus (SLE) and lupus nephritis (LN) and to evaluate their expressions and distributions in renal LN patients' biopsies. The frequencies of two SNP in the TLR-9 gene and one in the TLR-5 gene was examined in 106 SLE patients (among them 37 LN patients) and in 200 matched controls by polymerase chain reaction-restriction fragment-length polymorphisms (PCR-RFLP) analysis. TLR-9 and TLR-5 expressions were assessed by reverse transcription (RT)-PCR and immunohistochemistry carried on LN renal biopsies compared to healthy renal tissue. A significant genotypic and allelic association was revealed between TLR-9-rs352140 and both SLE and LN (P < 0·05). The TLR-9 transcript level was significantly higher in LN biopsies compared to control (P < 0·05). This increase was observed histochemically in the tubulointerstitial compartment. TLR-9 was detectable in LN glomeruli patients but not in normal control glomeruli. No allelic nor genotype association was found with TLR-5-rs5744168 in SLE. but the T allele and the TT genotype were raised significantly in the LN group (P < 0·05). A significant increase in TLR-5 gene expression in LN biopsies, which contrasted with normal kidneys (P < 0·05), was confirmed by an intense and diffuse staining for TLR-5 only in LN tubules (P < 0·05). Our data show that TLR-5 and TLR-9 are susceptible genes to LN and that their expression is dysregulated in LN patients' kidneys, supporting a role of these mediators in the pathogenesis of LN.

Telangiectatic osteosarcoma of the rib: a rare entity and a potential diagnostic pitfall.

Osteosarcoma (OS) is a common primary malignant tumor of bones that produces osteoid matrix. Telangiectatic osteosarcoma (TOS) is a rare variant of OS. It affects the long bones especially the lower end of femur and the upper ends of tibia and humerus, a distribution similar to the conventional osteosarcoma. The rib involvement is very infrequent. We present a case of TOS of the rib that posed a diagnostic difficulty owing to its unusual location and to its resemblance to giant cell tumor and aneurysmal bone cyst. Correspondence.

Chediak-Higashi syndrome presenting in accelerated phase: A case report and literature review.

Chediak-Higashi syndrome (CHS) is a rare autosomal recessive lysosomal disorder characterized by frequent infections, oculocutaneous albinism, bleeding diathesis, and progressive neurologic deterioration. In 85% of cases, CHS patients develop the accelerated phase characterized by pancytopenia, high fever, and lymphohistiocytic infiltration of liver, spleen, and lymph nodes. Treatment of accelerated-phase CHS is difficult and the prognosis is poor. Here, we report a case of CHS in a 2-year-old boy who presented in the accelerated phase of the disease. CHS diagnosis was made on the basis of clinical characteristics, hair analysis, and identification of pathognomonic giant azurophilic granules in peripheral blood and bone marrow.

An unusual tumour of the lung.

We report a case of a 51-year-old woman with a solitary mast cell tumour of the lung, a rare neoplasm with only three previously-reported cases reported in the literature. Unlike previous cases, the tumour in the present case was bulky, measuring 14 cm in diameter and budding into the segmental bronchus. Histologically, it showed proliferation of typical metachromatic mast cells intermingled with undifferentiated cells with a ratio of 3:1. The neoplastic mast cells stained strongly with tryptase, CD117, CD68 and CD45, CD14 and CD33; whereas the undifferentiated cells lacked all these markers and expressed EMA and cytokeratin. Histological examination of bone marrow and laboratory data were unremarkable. To our knowledge, this is the fourth case of solitary extracutaneous mastocytoma of the lung. The differentiating features of this neoplasm and a review of literature are presented.

[Pseudotumor phenotype of sarcoidosis: about two cases]. / Phénotype pseudotumoral de la sarcoïdose: à propos de deux cas.

INTRODUCTION: Sarcoidosis is a multisystem benign granulomatous disease of unknown etiology. It can sometimes cause diagnostic confusion by presenting in the form of a pseudotumor, thus constituting a trap for the unwary. COMMENTS: The authors report two cases of pseudotumor sarcoidosis. In the first, the pseudotumor occurred in the context of multisystem disease in a 48-year-old man. The response to treatment with systemic corticosteroids was complicated by the development of disseminated tuberculosis, which was rapidly fatal. The second case, by contrast, was about a 58-year-old woman and the disease was self-limiting, resolving spontaneously in less than 3 months. CONCLUSION: Through these two cases, the authors focus on the particularities of the pseudotumor manifestation of pulmonary sarcoidosis. The diagnosis is often difficult. The mismatch between the clinical picture and the extent of radiological lesions should, however, suggest the diagnosis. Histological evidence is needed to eliminate other etiologies including malignant tumors. The condition usually resolves either spontaneously or after treatment with systemic corticosteroids. However, relapses are possible, including on discontinuation of corticosteroid therapy.

[Mediastinal mature teratoma with spontaneous malignant transformation]. / Tératome médiastinal mature avec transformation maligne spontanée.

INTRODUCTION: Malignant teratomas can be either immature teratomas or they can develop after treatment of other malignant germ cell tumors with chemotherapy or radiotherapy. Spontaneous malignant transformation of mature teratomas is very rare. OBSERVATION: We report the case of a patient complaining of atypical chest pain. Chest plain radiography showed a right anterior mediastinal mass. Computed tomography revealed a heterogeneous mediastinal mass with fat areas and calcification. There were hilar and mediastinal lymph nodes as well as lung parenchymal nodules. CT-guided and then surgical biopsies confirmed the diagnosis of a mature teratoma, which had degenerated into a digestive adenocarcinoma. CONCLUSION: Spontaneous malignant transformation of mature mediastinal teratoma is very rare. The diagnosis of malignant transformation is based on radiological examinations, laboratory tests and histological studies.

[Appendicular cystadenocarcinoma with cutaneous fistula]. / Cystadénocarcinome appendiculaire fistulisé à la peau.

BACKGROUND: Cutaneous metastasis of colorectal cancer is rare. We report a case of fistular lesions of the buttocks revealing a mixed tumour of the appendix involving mucinous cystadenocarcinoma and carcinoid tumour. CASE REPORT: A 67-year-old woman was admitted for four skin fistulae of the right buttock present for 6 years. Histological examination of skin biopsy specimens identified infiltration of the dermis by metastatic mucinous adenocarcinoma while colonoscopy showed a caecal tumour measuring 4 cm. Surgical excision was performed involving right hemicolectomy, evacuation of retroperitoneal mucin collection and excision of fistulae. Histopathological examination of surgical specimen confirmed mixed tumour consisting of perforated mucinous cystadenocarcinoma and carcinoid tumour of the appendix. Recurrence of the fistular lesions was seen. The patient was hospitalized several times for surgical drainage of mucin. She died one year later. DISCUSSION: Cutaneous metastasis of colorectal cancer is an uncommon event that usually occurs after identification of the primary tumour and generally indicates advanced-stage disease and an ominous prognosis. This case is particular and underlines the need to rule out a metastatic origin of cutaneous fistulae, even in patients otherwise apparently in good health.

[Extrafollicular adenomatoid odontogenic tumour: report of two cases]. / Tumeur odontogène adénomatoïde extrafolliculaire: à propos de deux cas.

The purpose of this study was to analysis the clinicopathological features of adenomatoid odontogenic tumour extrafollicular and to discuss the diagnosis pitfull. We present two cases diagnosed and followed at the C.H.U. Habib Bourguiba, Sfax. It is about a 15 year-old boy and a 46 year-old woman who presented gingival swelling. The panoramic radiographs showed in both cases, a radiolucent area affecting teeth 23, 24 and 35 respectively. A computed tomography scan, realized at the second cas, demonstrated an expansile lesion with a sclerotic rim. An exploratory surgical approach was chosen and the final diagnosis was microscopically confirmed to be an extrafollicular variant of adenomatoid odontogenic tumour. The patients were healthy and have not shown any signs of recurrence at follow-up. The two cases described illustrate clinical and radiographic features of the extrafollicular variant of adenomatoid odontogenic tumour. Careful diagnostic procedure and adequate interpretation of radiographic findings may result in a correct diagnosis with otherwise may result in unnecessary endodontic treatment.

[Papillary carcinoma arising from dyshormonogenetic goiter]. / Cancer papillaire sur goitre dyshormonogénétique.

INTRODUCTION: Dyshormonogenetic goiter is a genetically determined thyroid hyperplasia due to an enzyme defect in thyroid-hormone synthesis. Malignant transformation is one of the most serious complications, rarely reported in the literature. OBSERVATION: We report a new case of a 13-year-old boy with goitrous hypothyroidism who consulted for a voluminous goiter. Total thyroidectomy was performed. Histopathological examination revealed multiple foci of papillary carcinoma with a lymph node metastasis. CONCLUSION: Dyshormonogenetic goiter is a rare entity, representing one of the causes of congenital hypothyroidism. It is morphologically characterized by architectural and cellular pleomorphism that may mimic thyroid malignancy and cause difficulties in differential diagnosis.

Small cell osteosarcoma: a case report.

INTRODUCTION: Small cell osteosarcoma (SCO) is a rare bone tumour representing 1.3% of all osteosarcomas. This rare variety of osteosarcoma tends to arise in the metaphysis of long bones and may extend secondary to epiphysis. By histopathology, the tumour is composed of small round cells with a variable degree of osteoid production. We report a new case of SCO in the distal femur with epiphyseal involvement. We also present the clinical, radiologic and therapeutic features of SCO with particular emphasis on the pathologic features that allow differentiation of this neoplasm from other small round cell tumours. OBSERVATION: A 14-year-old girl presented with a 6-month history of a painful tumefaction of the left knee with motor deficit. Imaging analysis of the knee demonstrated a lytic lesion of the metaphysis in addition to epiphysis of the distal femur with cortical destruction and invasion of soft tissues. Histological examination of a biopsy specimen showed sheets of neoplastic small round cells simulating Ewing's sarcoma. Osteoid was focally present. A diagnosis of SCO was made. The patient received 2 cycles of adjuvant chemotherapy with ifosfamide, adriamycin and cisplatin. MRI showed no change in tumour size. An en bloc, wide-margin resection of the lesion was performed. Histological examination showed a viable tumour with few necrotic foci. The patient received adjuvant chemotherapy with Holoxan and VP16. The clinical response was favourable. CONCLUSION: SCO is a rare clinical entity with a high grade of malignancy that must be distinguished from other round cell tumours, particularly Ewing's sarcoma, in order to optimise treatment protocols.

[Severe rectal bleeding in an Tunisian woman: colonic tuberculosis mimicking a tumor]. / Une rectorragie sévère sous les tropiques.

Since colonic tuberculosis is uncommon and its bifocal pseudo-tumor form is exceptional, differential diagnosis with the colonic cancer is exceedingly difficult. The purpose of this report is to describe a case of primary colonic tuberculosis in two separate locations discovered in a patient presenting with persistent massive hematochezia. A 69-year-old woman was examined for hematochezia, abdominal pain and recent weight loss. Colonoscopy revealed the presence of two ulcerated tumor-like lesions in right colon. One of these lesions caused significant stenosis. Histological examination of biopsy specimens was inconclusive. Colonic tumor with bleeding was considered as the most likely diagnosis. Surgical exploration demonstrated one tumor in the cecum and another in the ascending colon. Right hemicolectomy was performed. Histological examination of the surgical specimen demonstrated a granulomatous reaction pattern with caseous necrosis. Conventional antituberculosis treatment led to clinical improvement.

[A rare localization of solitary plasmocytoma]. / Une localisation rare de plasmocytome solitaire.

INTRODUCTION: Solitary bone plasmocytoma is rare, characterized by malignant plasmocyte proliferation, derived from a sole B lymphocyte clone located on a bony segment without medullar invasion. It, above all, affects the thoracolumbar spine. Costal involvement is rarely described. CASE REPORT: The authors report the case of a 60-year-old man who complained of dyspnea, dry cough, and thoracic pain four months before admission. Thoracic imaging revealed a left apical tissue mass with osteolysis of the first rib. A transparietal biopsy of the mass was not helpful. Surgical biopsy concluded as to the diagnosis of costal plasmocytoma. All of the examinations carried out to search for other localizations were negative confirming the solitary nature of the tumor. The treatment consisted of complementary radiotherapy at a dose of 45Gy. The patient was in remission after eight months. CONCLUSION: Solitary costal plasmocytoma should be called to mind when confronted with a lytic tumor of the rib. The treatment is based on surgery and radiotherapy. The prognosis is dominated by the risk of progression to multiple myeloma.

[Amelanotic spitzoid melanoma of the digit: case report]. / Melanome spitzoide achromique du doigt: à propos d'une observation.

BACKGROUND: Melanomas of digit is rare, accounting for 1% of all cutaneous melanomas. We report a new case. AIM: Our purpose is to discuss the clinicopathological characteristics and the difficulties encountred in establishing diagnosis of this rare tumor. OBSERVATION: we report the case of a 25-years-old woman, who consulted for nodular and ulcerated lesion of the right index, located in the external face of the metacarpo-phalangeal joint. The nodule was biopsied and histopathologic exam concluded to spitzoid melanoma. The surgical margins were involved. The patient refused surgical recovery. She consulted 3 years later with axillary lymph nodes. A wide excision of the tumor with lymph node biopsy were made. Histological study concluded to a tumoral residu incompletely excided with lymph node metastases. Amputation of the second digit with dissection of the axillary lymph nodes was made. The surgical margins were tumor free. Lung metastases appeared with a follow up of two months. The patient died early after starting chemotherapy with Deticen. CONCLUSION: In our report, clinical presentation was misleading causing a diagnosis and therapeutic delay. Pathologically, all the histological types of melanoma were described in the digit except spitzoid melanoma.

[Adenoid cystic carcinoma of the breast]. / Carcinome adénoïde kystique du sein.

Adenoid cystic carcinoma of the breast is a rare neoplasm, accounting for only 0.1% of all malignant breast tumours. It is more common in women in the sixth decade of their lives and often in the subareolar area. The clinical criteria is not specific and the radiographic examination showed a benign-appearing tumour. The preoperative diagnosis is possible with fine-needle aspiration cytology. The diagnosis is made by histological examination, presented a difficult differential diagnosis with cribriform carcinoma; so it is necessary to use histochemical or immunohistochemical techniques. The treatment is not well established. It consists of lumpectomy with radiation or mastectomy. Compared to other locations, adenoid cystic carcinoma of the breast has a favorable prognosis. Lymph node involvement or distant metastases seldom occur. The aim of our study is to describe the epidemiological, clinicopathological characteristics, the treatment and the prognosis of this rare type of breast tumour.