A quick, easy and efficient protocol for extracting high-quality RNA from Mycobacterium tuberculosis using a spin column commercial kit

RNA extraction from Mycobacterium tuberculosis has been a historically challenging task for researchers due to the thick lipids associated with the cell wall of this "notorious" pathogen that is responsible for Tuberculosis (TB) outbreaks. Several studies have successfully extracted RNA from M. tuberculosis using a Trizol reagent combined with organic solvents. Recently, our laboratory has successfully extracted high quality total RNA using a commercial kit from clinical strains belonging to F15/LAM4/KZN, Beijing and F11 strain families and H37Rv laboratory strain by exploiting high speed homogenizer for cell lysis and spin columns for RNA purification. The quality and integrity of the extracted RNA was analyzed and confirmed through the Nanodrop, Bioanalyzer and RNA 3-(N-morpholino) propanesulfonic acid (MOPS) gel electrophoresis. Furthermore, to confirm the integrity of small RNA (sRNA) molecules due to their vulnerability to degradation, the RNA samples were converted to cDNA and sRNAs were amplified and confirmed through PCR. This detailed RNA extraction protocol proposes to carve a new path into TB transcriptome research without the use of organic solvent for downstream purification steps while yielding high quality RNA that can be used to understand M. tuberculosis transcriptome regulation.

Immunohistochemical determination of mismatch repair gene product in colorectal carcinomas in a young indigenous African cohort

BACKGROUND

Colorectal cancer (CRC) in the indigenous African population of South Africa is uncommon (age standardised incidence rates of 11.29 for males and 7.27/100 000 for females) and tends to occur at a young age. Lynch syndrome (LS), an inherited mismatch repair (MMR) gene abnormality, accounts for 3-4% of newly diagnosed CRCs in high incidence areas. There is some evidence that the contribution of an MMR abnormality to the overall CRC burden may be increased in low incidence areas. We aimed to determine the prevalence of MMR deficiency in an indigenous African population.

METHODS

A cohort of 66 self-declared indigenous African patients, less than 50 years of age at diagnosis with CRC was identified from clinical and pathological records. The original histopathology was reviewed to confirm the diagnosis and features suggestive of MMR abnormality determined (pushing edge, mucinous, lymphocytic infiltration, Crohn's like reaction). Where sufficient tissue was available, samples were sectioned and stained for the four MMR proteins.

RESULTS

Histopathological examination confirmed adenocarcinoma in 31 individuals. At least one feature suggestive of MMR was identified in 22 of these specimens. Twenty-seven cases were stained for all four MMR proteins using standard immunohistochemistry (IHC). MMR deficiency was found in 37% (n = 10/27) of cases. Median age of diagnosis was 35 years in the MMR-proficient group and 44 years in the MMR-deficient group, p < 0.008. No other significant differences between the groups were noted.

CONCLUSION

MMR deficiency was common in colorectal carcinomas in the older patients in this cohort, but very young indigenous Africans CRCs do not appear to result from mismatch repair gene mutations.

Neuroendocrine neoplasms of the digestive tract: incorporating the 2019 WHO grading schema in the South African context

BACKGROUND

The classification of gastrointestinal (GI) neuroendocrine neoplasms (NENs) has been updated in the WHO classification of tumours of the digestive tract. Mitotic rate and Ki-67 proliferation index are central to the histopathological grading of these tumours. Assessing these variables is not standardised in local practice. This study addresses this deficit in the South African context.

METHODS

This is a retrospective audit of archival material of resection specimens of GI NENs (excluding appendix) at Groote Schuur Hospital from 2004 to 2017. We performed a mitotic count and immunohistochemistry for Ki-67 to reclassify tumours according to the 2019 WHO criteria.

RESULTS

Thirty-five resection specimens were examined. These represented stomach (n = 5), jejunoileum (n = 17), colon (n = 7) and rectum (n = 6). The mean age at the time of resection was 56 years (range 32-72). Twenty-one cases (60%) were women and 14 (40%) were men. The majority (24/35) of tumours were classified as grade 1 well-differentiated neuroendocrine tumours (WD NETs), 8/35 were classified as grade 2 WD NETs and 3/35 were classified as small cell poorly differentiated neuroendocrine carcinomas (PD NECs). Re-classification resulted in 7/35 (20%) changes in tumour grade (4 upgraded, 3 downgraded). In most instances (7/8), the Ki-67 proliferation index was the determining factor in assigning tumour grade.

CONCLUSION

This study has increased awareness of the recently updated WHO classification system. We conclude that an objective and systematic approach to counting of mitoses and determination of the Ki-67 proliferation index is recommended in routine practice.

Optimized Procedure for Recovering HIV-1 Protease (C-SA) from Inclusion Bodies

HIV-1 is an infectious virus that causes acquired immunodeficiency syndrome (AIDS) and it is one of the major causes of deaths worldwide. The production of HIV-1 protease (PR) on a large scale has been a problem for scientists due to its cytotoxicity, low yield, insolubility, and low activity. HIV-1 C-SA protease has been cloned, expressed, and purified previously, however, with low recovery (0.25 mg/L). Herein we report an optimal expression and solubilisation procedure to recover active HIV-1 C-SA protease enzyme from inclusion bodies. The HIV protease was expressed in seven different vectors (pET11b, pET15b, pET28a pET32a, pET39b, pET41b and pGEX 6P-1). The highest expression was achieved when the vector pET32a (Trx tag) was employed. A total of 19.5 mg of fusion protein was refolded of which 5.5 mg of active protease was obtained after cleavage. The free protease had a high specific activity of 2.81 µmoles/min/mg. Interestingly the Trx-fusion protein also showed activity closer (1.24 µmoles/min/mg) to that of the free protease suggesting that the pET32a vector (Trx tag) expressed in BL21(DE3) pLysS provides a more efficient way to obtain HIV-1 protease.

Comparison of the lipid properties of healthy and pansteatitis-affected African sharptooth catfish, Clarias gariepinus (Burchell), and the role of diet in pansteatitis outbreaks in the Olifants River in the Kruger National Park, South Africa

Pansteatitis has been identified in wild populations of sharptooth catfish, Clarias gariepinus (Burchell), and Nile crocodiles, Crocodylus niloticus Laurenti, inhabiting the same waters in the Olifants River Gorge in the Kruger National Park, South Africa. Mesenteric and pectoral fat tissue was investigated microscopically and by fatty acid analysis in healthy and pansteatitis-affected catfish from both captive and wild populations. Variation in fatty acid composition between pectoral and mesenteric fat was noted. Composition of mesenteric fat differed between fish from various localities as a result of differences in diet. Pansteatitis in the captive population, resulting from ingestion of high amounts of dietary oxidized fat, reflected higher levels of unsaturated fatty acids within the mesenteric fat. Mesenteric fat of pansteatitis-affected wild catfish was characterized by an increase in moisture content, a decrease in fat content and a decrease in stearic and linoleic acids. The n-3 to n-6 fatty acid ratio of mesenteric fat was higher in pansteatitis-affected wild catfish than in healthy catfish from the same locality, reflecting higher polyunsaturated fat intake by pansteatitis-affected fish. The possible role of alien, invasive, phytoplankton-feeding silver carp, Hypophthalmichthys molitrix (Valenciennes), in the aetiology of pansteatitis in both catfish and crocodiles in the Olifants Gorge is discussed.

Steatitis in wild sharptooth catfish, Clarias gariepinus (Burchell), in the Olifants and lower Letaba Rivers in the Kruger National Park, South Africa

Large numbers of adult Nile crocodiles, Crocodylus niloticus (Laurenti), died from pansteatitis during autumn and winter 2008 in the lower Letaba and Olifants River gorge in the Kruger National Park, South Africa. Consequently, the health status of fish from these waters was investigated. The study presents the pathological findings in fish inhabiting these rivers within the boundaries of the Park. Changes typical of steatitis were diagnosed in many of the larger specimens of sharptooth catfish, Clarias gariepinus (Burchell), caught within the Olifants River gorge. These fish carried large amounts of mesenteric fat with characteristic small brown granulomata within the adipose tissue. Necrosis and inflammation of the adipose tissues, with characteristic ceroid accumulation within the resultant granulomata and the associated aggregation of ceroid-containing macrophages, were demonstrated histologically and were typical of steatitis. Other changes included mild thickening and pallor of the gill tissues and swollen, orange, fatty livers. Focal hepatic lipidosis was demonstrated histologically, and special stains revealed storage of large amounts of iron in the livers. Blood smears revealed chromatin clumping in erythrocyte nuclei and nuclear and cell membrane irregularities. This is the first record of steatitis in wild-caught C. gariepinus.

Piroplasm parasites of white rhinoceroses (Ceratotherium simum) in the Kruger National Park, and their relation to anaemia

As part of a larger survey to map the geographical distribution of Babesia and Theileria parasites in the southern African rhinoceros population, white rhinoceroses were sampled during routine immobilisations in the Kruger National Park. Polymerase chain reaction (PCR) and reverse line blot (RLB) hybridisation assays were used to screen for the presence of piroplasms and complete blood counts were used to assess associated changes in clinical parameters. Of the 195 rhinoceroses sampled, 71 (36.4 %) tested positive for the presence of Theileria bicornis, with no significant change in the haematological parameters measured, while 18 (9.2 %) tested positive for Theileria equi. None of the rhinoceroses sampled tested positive for Babesia bicornis, a parasite associated with mortalities in black rhinoceroses.

Piroplasm parasites of white rhinoceroses (Ceratotherium simum) in the Kruger National Park, and their relation to anaemia

As part of a larger survey to map the geographical distribution of Babesia and Theileria parasites in the southern African rhinoceros population, white rhinoceroses were sampled during routine immobilisations in the Kruger National Park. Polymerase chain reaction (PCR) and reverse line blot (RLB) hybridisation assays were used to screen for the presence of piroplasms and complete blood counts were used to assess associated changes in clinical parameters. Of the 195 rhinoceroses sampled, 71 (36.4 %) tested positive for the presence of Theileria bicornis, with no significant change in the haematological parameters measured, while 18 (9.2 %) tested positive for Theileria equi. None of the rhinoceroses sampled tested positive for Babesia bicornis, a parasite associated with mortalities in black rhinoceroses.

Piroplasm parasites of white rhinoceroses (Ceratotherium simum) in the Kruger National Park, and their relation to anaemia

As part of a larger survey to map the geographical distribution of Babesia and Theileria parasites in the southern African rhinoceros population, white rhinoceroses were sampled during routine immobilisations in the Kruger National Park. Polymerase chain reaction (PCR) and reverse line blot (RLB) hybridisation assays were used to screen for the presence of piroplasms and complete blood counts were used to assess associated changes in clinical parameters. Of the 195 rhinoceroses sampled, 71 (36.4 %) tested positive for the presence of Theileria bicornis, with no significant change in the haematological parameters measured, while 18 (9.2 %) tested positive for Theileria equi. None of the rhinoceroses sampled tested positive for Babesia bicornis, a parasite associated with mortalities in black rhinoceroses.

Anaplastic nephroblastomas express transketolase-like enzyme 1

AIM

Transketolase-like enzyme 1 (TKTL1) is a glycolytic enzyme that has been found to be upregulated in several tumours, and it is associated with tumour progression. Nephroblastoma is the commonest paediatric renal malignancy and has a good prognosis except for those with anaplasia. To the best of the authors' knowledge, the expression of TKTL1 in nephroblastomas has not been studied before and the aim of this study was to compare the immunoexpression of TKTL1 in anaplastic and non-anaplastic nephroblastomas.

METHODS

Twenty-eight patients who had nephrectomies for nephroblastomas were studied. Archival formalin-fixed paraffin-wax-embedded tissue sections were stained with monoclonal TKTL1 antibody.

RESULTS

Six of the 15 anaplastic nephroblastomas showed staining in 80-100% of the tumour (p = 0.36). None of the 13 non-anaplastic nephroblastomas showed TKTL1 staining in >80% of the tumour.

CONCLUSION

TKTL1 expression is associated with the presence of anaplasia and may be a mechanism via which anaplastic tumour cells thrive under different conditions. Glycolytic inhibitors may play a role in anaplastic nephroblastomas.

Biochemical and immunohistochemical characterisation of mucins in 8 cases of colonic disease--a pilot study

OBJECTIVES

To characterise mucins in cancer of the colon and compare these with controls using stringent biochemical measures to avoid endogenous proteolysis.

DESIGN

Crude mucus scrapings were collected from 12 specimens obtained by colectomy. Specimens from 3 traumatic colectomies and 1 sigmoid volvulus were used as controls, and compared with 6 specimens from colons resected for adenocarcinoma and 2 irradiated colons.

SUBJECTS

The median age of the 4 female patients was 76 years (range 49 - 82 years), and of the 8 male patients 46.5 years (range 16 - 74 years).

RESULTS AND CONCLUSIONS

The crude mucus scrapings in the 9 specimens ranged in weight from 353 mg to 7 697 mg (median 4 928 mg). The median of purified mucin in the 9 specimens was 0.72 microg/mg wet weight of scraped material. Eight samples gave non-extractable pellet material, and were treated with DTT to reduce disulphide bonds for further analysis. One of these 8 pellets was resistant to reduction and had to be digested with papain before analysis. Only 5 of these pellets had mucin. Gel filtration and SDS-PAGE (sodium dodecyl sulphate polyacrylamide gel electrophoresis) analysis revealed different populations of mucin based on size and extent of degradation. Western blotting and immunohistochemical analysis confirmed the presence of MUC2 in all samples, MUC5AC in 2 and MUC5B in 5 diseased specimens. Immunohistochemical analysis showed that there was no MUC1 in the normal specimens, MUC1 apoprotein (MUC1 core) in 2 cancer specimens and MUC1 in 1 cancer specimen. Histochemical analysis showed that normal tissue expressed neutral and acidic mucins and diseased specimens predominantly expressed acidic mucins. The electrophoretic behaviour of MUC2 in sigmoid volvulus was different from that in cancer of the colon.

Microsatellite analysis of the adenomatous polyposis coli (APC) gene and immunoexpression of beta catenin in nephroblastoma: a study including 83 cases treated with preoperative chemotherapy

AIMS

To determine whether microsatellite mutations of the adenomatous polyposis coli (APC) gene have pathological or prognostic significance in nephroblastomas and to correlate APC alterations with beta catenin immunoexpression.

METHODS

One hundred nephroblastomas were analysed, 83 of which received preoperative chemotherapy. Normal and tumour DNA was isolated using standard proteinase K digestion and phenol/chloroform extraction from paraffin wax embedded tissue. Polymerase chain reaction using four APC microsatellite markers-D5S210, D5S299, D5S82, and D5S346-was performed and the products analysed. Immunohistochemistry was performed using the LSAB kit with diaminobenzidine as chromogen. Results were correlated with clinicopathological data using the chi(2) test.

RESULTS

Allelic imbalance/loss of heterozygosity was more frequent than microsatellite instability, with 30% of cases showing allelic imbalance/ loss of heterozygosity and 16% showing microsatellite instability. Although there was a significant correlation between the results for individual markers and the clinicopathological data, the overall results do not support a prognostic role for APC in nephroblastoma. Expression of beta catenin was seen in 93% of cases. Staining was predominantly membranous, with epithelium, blastema, and stroma being immunoreactive. Cytoplasmic redistribution was seen in 58% of cases, but no nuclear staining was detected. No significant associations between beta catenin expression and the clinicopathological parameters were found. Kaplan-Meier survival plots showed that patients with loss of membranous staining and pronounced cytoplasmic staining (score, 3) had a significantly shorter survival (p = 0.04; median survival, 5.87 months).

CONCLUSION

Microsatellite analysis of APC and immunoexpression of beta catenin did not provide significant pathological or prognostic information in this cohort of nephroblastomas.

Sertoli cell nodules in the undescended testis: a histochemical, immunohistochemical, and ultrastructural study of hyaline deposits

AIMS

To document the morphology, immunohistochemical staining properties, and ultrastructural features of hyaline material in Sertoli cell nodules of undescended testis and contrast them with those of sex cord tumour with annular tubules (SCTAT), which is histologically similar. To highlight the need to distinguish these nodules from other Sertoli cell hyperplasias, such as intratubular Sertoli cell proliferations, which occur in specific clinical contexts.

MATERIALS/METHODS

A retrospective study of 46 orchidectomy specimens from cryptorchid testes, 27 of which contained Sertoli cell nodules. Special histochemical stains, immunohistochemical stains for type IV collagen and fibronectin, and ultrastructural examination of the hyaline material were performed using tissue from paraffin wax embedded tissue blocks.

RESULTS

The hyaline deposits in SCTAT and Sertoli cell nodules had similar staining patterns-periodic acid Schiff (PAS) and PAS-diastase positivity with variable staining of Martius scarlet blue and Masson trichrome. Type IV collagen immunoreactivity was seen in hyaline areas, although fibronectin was negative. Electron microscopy of hyaline areas confirmed a compact matrix identical to components of the basement membrane in the adjacent seminiferous tubules.

CONCLUSION

This study describes an unusual form of Sertoli cell proliferation in undescended testes, which must be distinguished from Sertoli cell tumours and other forms of proliferation. In addition, the hyaline material within Sertoli cell nodules in the cryptorchid testis is histochemically, immunohistochemically, and ultrastructurally consistent with both matrix and fibrous components of seminiferous tubule basement membranes. Increased production of basement membrane material, with subsequent invagination into tubules, is the most likely origin of this material.

Primary tumours of the liver in children: an African perspective

Primary tumours of the liver present diagnostic and management difficulties. In Africa, outcomes reflect limitations imposed by comorbidity and lack of resources, both human and material, for major liver resection. Whilst hepatoblastoma and hepatocellular carcinoma can be readily distinguished on clinical and biochemical grounds, there is a high incidence of sarcomatous tumours that mandate biopsy. In our experience, hepatocellular carcinoma in childhood is a lethal condition, usually bilateral and associated with hepatitis B infection. Sarcomatous tumours are often resectable but have a high rate of local recurrence. Hepatoblastoma is a surgically curable tumour in many patients. Resection for benign liver tumours can be safely accomplished and augments institutional experience with major liver surgery.

Malignant solid tumours in neonates: an African perspective

Malignant tumours in the neonate are distinct pathologically, clinically, and therapeutically from those in older children or adults. Behaviour cannot be directly implied from the histological appearance, and risk stratification is therefore difficult and complex. We review 42 patients seen over a 20-year period. Neuroblastoma (NB) was the commonest tumour seen (11), but the soft-tissue sarcomas were the dominant group (14). The initial management was surgical when possible. Chemotherapy, despite appropriate dose reduction, had significant morbidity and mortality. Whilst the outcome for congenital fibrosarcoma was good (6/7, 86%), there were no survivors amongst 5 patients with rhabdomyosarcoma. In the absence of cytogenetic and biochemical markers, risk stratification amongst babies with NB was based upon INSS staging. Stage I disease was associated with a good prognosis, whilst stage IV disease was uniformly fatal. Stage IVs disease had only 50% early survival. Patients with renal tumours, whether nephroblastoma or mesoblastic nephroma, did well. Only patients with morphologically immature teratomas were included, amongst whom there are 2 of 7 (29%) known survivors, but 43% have been lost to follow-up and their status is unknown. These figures are consistent with other reports from Africa.

ALK protein expression in rhabdomyosarcomas

AIMS

The ALK p80 chimeric protein is thought to be up-regulated as a result of the t(2;5) as classically seen in anaplastic large cell lymphoma. However, rhabdomyosarcomas (in particular, the alveolar subtype) have also been noted to show expression of this protein. This study set out to examine ALK expression in a large number of rhabdomyosarcomas.

METHODS AND RESULTS

Eighty-three cases of rhabdomyosarcomas and 16 cases of malignant mixed müllerian tumours with a rhabdomyosarcomatous component were retrieved from the archives of the Department of Anatomical Pathology for the period 1983-2001. The sections were stained with polyclonal ALK antibody. There were 52 male and 30 female patients. In one case, the gender of the patient was not indicated. The ages ranged from 1 week to 77 years. The most common site was the head and neck region, followed by the pelvis and extremities. Thirty-one cases were of the alveolar subtype while 40 cases were embryonal. There were four mixed embryonal/alveolar, six pleomorphic and two unclassifiable rhabdomyosarcomas. Fourteen of the 31 (45%) alveolar rhabdomyosarcomas stained positively for the ALK protein, while only six of the 40 embryonal (15%) cases showed positivity. One case each of the mixed embryonal/alveolar, pleomorphic and unclassified cases was also immunopositive. The rhabdomyosarcomatous component in the malignant mixed müllerian tumours was positive in four of the 16 cases.

CONCLUSION

We conclude that a proportion of alveolar rhabdomyosarcomas (in particular) exhibit ALK protein expression. However, ALK expression is not restricted to this subtype. An extension of this study is to determine if this over-expression is as a result of the t(2;5) translocation.

Rectal gastric heterotopia in infancy

Heterotopic gastric mucosa is rare in children with most cases presenting in association with Meckel's diverticulum. The authors present a 2-year-old boy with gastric heterotopia of the anorectum, who presented with painless, intermittent rectal bleeding.

Right pulmonary artery sarcoma

A 57-year-old man presented with cough, chest pain and dyspnea. Peripheral lung opacities detected radiologically on admission were surgically resected and histologically confirmed as pulmonary infarcts. Subsequent radiological examinations revealed a stricture of the right pulmonary artery with evidence of pulmonary hypertension. The patient was commenced on anticoagulant therapy, which resulted in some clinical improvement. A hilar mass detected later was resected together with the right lung. Pathological examination of the hilar mass revealed a tumour within the lumen of the pulmonary artery causing almost total occlusion of the artery. Histology showed angiosarcomatous and osteosarcomatous areas. The patient is well and disease-free 9 months following resection.

Primary lumbosacral Wilms tumour associated with occult spinal dysraphism

A 4-year-old child presenting with sudden-onset paraplegia and a sacral tumour in association with spina bifida occulta is reported. There were no stigmata of spinal dysraphism at birth. Imaging studies confirmed a sacral tumour with extradural extension up to T10 and spinal dysraphism. The histological features of the extradural and sacral components of the tumour were consistent with a Wilms tumour. The differential diagnosis included a primary sacral teratoma containing Wilms tumour elements or a primary extrarenal Wilms tumour arising in association with a spinal dysraphism. There was no clinical response to chemotherapy or radiotherapy.

Extraskeletal osteosarcoma of the scalp

A rare case of extraskeletal osteosarcoma of the scalp in a 56-year-old woman is described. At presentation she was found to have an 8-cm diameter, tender, firm, exophytic scalp tumor. MRI scan confirmed absence of underlying skeletal origin and showed extension along the subcutaneous plane. The tumor was excised and the patient received post-operative chemotherapy. Histologically, the tumor showed classical features of an osteogenic osteosarcoma with focal fibroblastic areas. In addition, there were rhabdoid cells present, which showed paranuclear cytoplasmic immunoreactivity for epithelial membrane antigen. The patient developed metastatic disease 6 months after surgical excision.

An unusual presentation of solitary fibrous tumor

STUDY DESIGN

Case report of a lumbar extradural solitary fibrous tumor.

OBJECTIVE

To describe the clinical manifestations and successful treatment of a patient with solitary fibrous tumor of the lumbar spine.

SUMMARY OF BACKGROUND DATA

Solitary fibrous tumor usually occurs on the pleura but has been described in a growing number of sites. Although this is the first case in a lumbar extradural location, clinicians should be aware of the many guises in which this entity appears. Most cases are benign and cure is effected by surgical extirpation.

METHODS

The diagnosis, treatment, and outcome of a patient with a lumbar extradural solitary fibrous tumor are reviewed.

RESULTS

A patient showing signs of myeloradiculopathy was found, by means of magnetic resonance imaging, to have an intensely enhancing extradural lesion in the region of L1. Excision biopsy revealed features of a solitary fibrous tumor. The patient made a rapid, complete recovery.

CONCLUSIONS

Solitary fibrous tumor has protean clinical manifestations and should be be considered in the differential diagnosis of intraspinal enhancing lesions on either side of the dura.

Intracranial mass lesions in HIV-positive patients--the KwaZulu/Natal experience. Neuroscience AIDS Research Group

BACKGROUND

Neurological disease heralds the development of AIDS in 10-20% of HIV-seropositive individuals. In over half of these cases the presentation will be that of an intracranial mass lesion (IML). In developed countries toxoplasmosis is the most frequent cause of IML in a positive patient, followed by primary central nervous system lymphoma. Less common causes include tuberculomas, cryptococcomas, abscesses and gummas. As a result of these observations, the algorithm adopted in developed countries calls for initial empirical treatment for toxoplasmosis. Biopsy of the IML is only considered if there is no response to treatment after 10-14 days. Whether such an algorithm would be applicable to the local population is unknown.

OBJECTIVE

We undertook a prospective study to determine the type and frequency of IML in local HIV-seropositive patients. A secondary objective, based on the findings, was to develop a local algorithm of management.

PATIENTS AND METHODS

Over a 17-month period HIV-seropositive individuals with an IML were entered into the study. Biopsy or aspiration of the lesion was performed either stereotactically or free-hand. Tissue obtained was processed for routine and special histological studies.

RESULTS

In the 38 cases where tissue was obtained, the most frequent cause of the IML was toxoplasmosis followed by encephalitis of obscure origin', brain abscess and tuberculoma/mycobacterial infection.

CONCLUSION

This study demonstrated that the spectrum of IML seen locally was similar to that in developed countries. The management protocol used elsewhere was therefore adopted for local patients.

Cytomegalovirus-induced syringosquamous metaplasia

An unusual case of syringosquamous metaplasia of the eccrine ducts caused by cytomegalovirus (CMV) is presented. The patient was HIV positive and had extensive excoriation of the perineum and vulva. Biopsy revealed the presence of herpes simplex virus (HSV) inclusions in the necrotic exudate, a CMV vasculitis and extensive involvement of the eccrine ducts. In addition to containing typical CMV inclusions, the eccrine ducts showed proliferation and squamous metaplasia. Inclusions of HSV were not seen within the eccrine ducts by light microscopy or immunohistochemistry. The extensive proliferation with accompanying squamous metaplasia superficially can resemble an infiltrating squamous carcinoma, but this was not evident to a great extent in this case. To the best of our knowledge, our case represents the first of syringosquamous metaplasia of eccrine ducts caused by CMV infection.

Follicular thyroid carcinoma with rhabdoid phenotype

The aim of this paper is to highlight the occurrence of an unusual histological variant of follicular carcinoma of the thyroid. Three cases are presented: each of the tumours contained a significant population of rhabdoid cells (accounting for 30-40% of the total tumour content). They were all found in female patients aged 65, 43 and 56 years, who presented with enlarged thyroid glands and were subjected to lobectomies. The tumours contained foci of well-differentiated follicular carcinoma, with areas of capsular and vascular invasion, and an accompanying rhabdoid cell component that merged with the neoplastic follicles. Immunohistochemically, the follicular component was positive with thyroglobulin, but the rhabdoid cells were negative in all three cases. The cytoplasmic aggregates in the rhabdoid cells were strongly positive for epithelial markers and vimentin. Two tumours pursued an aggressive biological course similar to other composite extrarenal rhabdoid tumours. A rhabdoid component accompanying thyroid follicular carcinomas is an adverse prognostic factor.

Malakoplakia and tuberculosis

A 33 year old woman developed a soft mass in the left anterior neck following treatment for pulmonary tuberculosis. An incisional biopsy was performed and a cold abscess drained. Histology confirmed a diagnosis of tuberculosis. In addition, there were numerous intracellular bodies which resembled the Michaelis-Gutmann bodies of malakoplakia. This case however displayed some atypical histological, histochemical and ultrastructural features, which are highlighted in this report. The mass responded to combination antituberculous treatment.

Recurrent Wilms' tumour or retroperitoneal teratoma? A challenging case

The clinical and pathological features of a left renal tumour and a subsequent retroperitoneal tumour in a 2-year-old boy are presented. The nephrectomy specimen showed typical features of a triphasic Wilms' tumour with focal heterologous elements and intralobar nephrogenic rests. The tumour was assessed as clinical stage III and post-operative chemotherapy and radiotherapy were administered. A retroperitoneal mass, detected following completion of postoperative therapy, was mainly made up of skeletal muscle and mature adipose tissue. Nests of epithelium resembling ameloblastic nests and a unique structure reminiscent of a developing tooth were present.

Ectomesenchymoma of the prostate: histological diagnostic criteria

A 5-month-old infant with an ectomesenchymoma (EMCH) of the prostate is described. The tumour was composed of embryonal rhabdomyosarcoma (RMS) and ganglioneuroma. Eight months after presentation the patient died of recurrent tumour, which caused intestinal obstruction. The tumour was initially diagnosed as an embryonal RMS on trans-rectal needle biopsies. The diagnosis of an EMCH is difficult if not impossible to make on needle-biopsy specimens. We suggest that pathologists should always consider an EMCH when confronted with a RMS or neuroectodermal tumour, and the use of immunohistochemical stains is recommended in this situation.

Clear cell (glycogen-rich) rhabdomyosarcoma presenting as cervical lymphadenopathy

A 15-year-old patient is described who presented with cervical lymphadenopathy. A lymph node biopsy confirmed a metastatic neoplasm composed of islands and aggregates of round to polygonal-shaped cells with surrounding hyalinised fibrous stroma. The tumour cells contained a clear glycogen-rich cytoplasm and stained for desmin, muscle-specific actin and sarcomeric actin. Electron microscopy revealed paranuclear thick and thin filaments. These findings confirm striated muscle differentiation and a diagnosis of glycogen-rich clear cell rhabdomyosarcoma. The tumour recurred in a cervical lymph node after 2 years. This is yet another tumour that must be considered in the differential diagnosis of clear cell tumours of the head and neck region.

Granuloma inguinale (donovanosis) presenting as a neck mass in an infant

A case of granuloma inguinale (GI) presenting as a lateral neck mass in a 4-month-old, HIV-positive infant is described. The histological features of the mass were typical of GI, with numerous macrophages containing intracellular organisms with a "closed-safety-pin" appearance. This is a rare occurrence, and the mode of transmission of infection is discussed. An awareness of GI in infants by both clinicians and pathologists is important to prevent morbidity and allow for prompt institution of appropriate treatment.

Primary hepatic osteosarcoma: case report and literature review

We describe a primary osteosarcoma of the liver in a 72 year old man. The man was symptomatic and had suffered abdominal pain and distension for four months before he died. At autopsy a large tumor of the liver with direct extension into adjacent structures was found. There was no evidence of primary tumor or primary bone lesion at any other site. Histologically, the tumor comprised malignant cells producing abundant osteoid arranged in a lace-like pattern. Smaller chondroblastic and fibroblastic components were also present. These findings were in keeping with a diagnosis of primary hepatic osteosarcoma.

Primary myxoid liposarcoma with rhabdomyoblastic differentiation

We report a unique case of primary myxoid liposarcoma of the floor of the mouth, in which well-differentiated rhabdomyoblasts were present. The tumor was incompletely excised. The patient is free of recurrence or metastasis following a course of radiotherapy. Heterologous components found in a liposarcoma include leiomyosarcoma, rhabdomyosarcoma, chondrosarcoma, osteosarcoma, and angiosarcoma. These elements have been described mainly in dedifferentiated liposarcomas situated in the retroperitoneum. To our knowledge, there has been only one report of a liposarcoma with rhabdomyosarcomatous differentiation occurring in the absence of a dedifferentiated component. The clinical implications of the presence of heterologous components without dedifferentiation are unclear.

p53 protein expression in nephroblastomas: a predictor of poor prognosis

Alteration of the tumour-suppressor gene p53 is the commonest genetic change encountered in human malignant tumours. A study was undertaken to ascertain the prognostic value of p53 immunoexpression in nephroblastomas. A series of 93 consecutive cases was analysed. Archival formalin-fixed, paraffin wax-embedded tissue sections were stained with monoclonal anti-p53 antibody (DO-7, Dako) using a peroxidase-labelled streptavidin biotin kit. Five of seven tumours (71.4%) with unfavourable histology, but only 3 of 86 favourable histology tumours, showed 'high' p53 immunoexpression (P < 0.001). p53 expression in unfavourable histology tumours was present in both anaplastic and non-anaplastic components. Moreover, there was uniform staining of blastema, epithelium and stroma in unfavourable histology tumours. No statistical difference in p53 expression was found between patients who had received and those who had not received preoperative chemotherapy (P = 0.678). Similarly, no statistical difference was found in the groups of patients who were disease free, who had residual/recurrent disease or who had died (P = 0.238). The mean survival period for patients with tumours that had 'low' and 'high' expressions was 24.8 months and 12.6 months respectively (P = 0.0003). In conclusion, p53 immunoexpression in nephroblastomas was found to be an important determinant of poor prognosis as it identifies those patients with a shorter survival period and also those with unfavourable histology tumours. It may also be of practical value to the practising pathologist by identifying those tumours that require careful assessment for the presence of anaplasia.

Perineurioma: an unusual cause of an external auditory canal polyp

A 33-year-old woman presented with pruritus of the right ear and on examination was found to have 1 x 1 cm polypoid lesion in the external auditory canal. This was removed and histological examination revealed a well-circumscribed spindle cell lesion arranged in fascicles and whorls. Immunohistochemistry showed the tumor to be EMA-positive but S-100-, desmin-, actin-, and cytokeratin-negative. Ultrastructural examination confirmed perineurial cell origin. There are several lesions in which perineurial cells are present, but a true perineurioma is composed exclusively of perineurial cells. It has characteristic morphological, immunohistochemical and ultrastructural features that help separate it from other nerve and neuroectodermal lesions.

Granuloma inguinale (donovanosis): an unusual cause of otitis media and mastoiditis in children

Granuloma inguinale (donovanosis) is seen predominantly in adults (it rarely occurs in children) and mainly affects genital skin and mucosa. Infection occurs at other skin and mucosal sites, and hematogenous dissemination to bone also has been described. The infection responds dramatically to appropriate antibiotic treatment. We present two cases of granuloma inguinale occurring in children (8 months and 5 months of age) causing mastoiditis and external ear discharges. A temporal lobe abscess also developed in the 8-month-old child. Subsequent computed tomography scans showed marked improvement in the brain lesion after treatment. The second child had a polypoid mass in the middle ear that on biopsy showed the features of granuloma inguinale. The mother of this child had biopsy-proven granuloma inguinale of the uterine cervix. These cases indicate that granuloma inguinale can be transmitted during vaginal delivery, and careful cleansing of neonates born to infected mothers is recommended.

Lung carcinomas composed of rhabdoid cells

Rhabdoid tumours form a distinctive morphological entity that is associated with aggressive biological behaviour. They have been described in several sites and tumour types. This paper presents three new cases of rhabdoid lung cancers. Lung cancers were analysed for the presence of cells with the rhabdoid phenotype: eccentric vesicular nuclei and abundant eosinophilic cytoplasm. Cells displaying this morphology were then subjected to immunohistochemistry and electron microscopy. The relevant clinical data on these cases were then accessed. Three cases conforming to the morphological, immunophenotypic and ultrastructural characteristics of rhabdoid cells were identified. Two of the cases were associated with foci of adenocarcinoma and the remaining case was a large cell neuroendocrine carcinoma. Two of the cases showed rapid clinical courses with the patients dying of disease within 6 months. Lung tumours with a rhabdoid phenotype are uncommon but are noteworthy because of their aggressive behaviour and, hence, poor prognosis.