An experimental model for amoebic abscess production in the cheek pouch of the Syrian golden hamster, Mesocricetus auratus.

A new experimental model was developed in hamsters for amoebic abscess caused by Entamoeba histolytica. E. histolytica trophozoites were cultured in a liquid axenic medium, and then injected intradermally into the cheek pouch of the Syrian golden hamster, Mesocricetus auratus. Inoculation consistently resulted in abscess formation at the site in 20 of 22 (91%) study animals. The amoebic nature of the abscesses was confirmed by light microscopy and histopathologic examination. Abscess formation was maximal at day 12 post-inoculation. Potential applications of this simple and reliable model include further elucidation of the pathogenesis of invasive amoebiasis, studies of the host response to amoebae, and in vivo evaluation of chemotherapeutic agents that show in vitro efficacy against E. histolytica.

Massive lower gastrointestinal bleeding due to Dieulafoy lesion of colon.

A 25-year-old man with massive lower gastrointestinal bleeding underwent emergency mesenteric angiography. An actively bleeding lesion was found in the cecum. Right hemicolectomy was performed. Histology revealed a Dieulafoy lesion of the cecum. This is an extremely rare lesion responsible for massive lower GI bleeding.

Mantle cell lymphoma presenting as solitary polypoid colonic lesions.

Mantle cell lymphoma of the intestine is rare, usually presenting as multiple small polyps. We report three men with colonic mantle cell lymphoma in the form of single large polypoid mass. The clinical picture suggested adenocarcinoma; the diagnosis was made at histology and immunohistochemistry of the colectomy specimens.

Morphological pattern of salivary gland tumours.

OBJECTIVE: To delineate the spectrum of salivary gland tumors in our setup. SETTING: The Aga Khan University Medical Centre, Karachi. METHOD: Tumors were analysed considering histological type, age and sex of the patients and anatomic location. The diagnosis of individual tumours was based on the 1991 World Health Organisation Classification. RESULTS: During the span of eight years (1991-1998), 379 cases of salivary gland tumours were diagnosed. Of these, 205 (65.7%) were male and 174 (34.3%) were female. The median age at the time of diagnosis was 35 years. The median age for patients with malignant lesions (44 years) was 12 years older than those with benign tumours (34 years). Overall, malignant tumours were seen more frequently in males, however benign tumours were distributed equally between the two sexes. The most common site was parotid gland (82.85%). Only five cases of minor salivary gland tumours were seen. The most frequently diagnosed benign salivary gland neoplasm was pleomorphic adenoma (84.5%), followed by Warthin's tumours (6.18%), Mucoepidermoid carcinoma was the most commonly encountered malignant lesion (56.9%), followed by adenoid cystic carcinoma (19.6%). CONCLUSION: Plemorphic adenoma was the most common benign salivary gland tumour and mucoepidermoid carcinoma was the most frequent malignant neoplasm. Parotid gland was the most common site of origin in both benign and malignant tumours. The overall relative frequency of salivary gland tumours in this series correlates with that reported in the international literature.

Breast carcinoma in Pakistani females: a morphological study of 572 breast specimens.

OBJECTIVE: To study the morphological features in breast carcinoma which have proven prognostic value. METHODS AND SETTING: A retrospective analysis of 572 mastectomy specimens received over a period of three years at the department of pathology, The Aga Khan University Hospital. RESULTS: A total of 572 mastectomy specimens were analyzed which were received over a period of three years. Most of the patients were in the 5th and 6th decades of life. The mean age at diagnosis was 48 years. The most common tumour was infiltrating ductal carcinoma (81%). Tumour size was > 2 cms. in 80% of the cases. According to Modified Bloom and Richardson system most of the tumours were in grade II (65%) followed by grade III (24%). The number of cases with > 3 lymph node metastasis was significantly higher (70%) in tumours of > 2 cms size. High grade tumours also showed increased number of lymph node involvement. CONCLUSION: In Pakistani females breast carcinoma occurs at a younger age group. They are of large size at the time of presentation and show more frequent axillary lymph node metastasis. Infiltrating ductal carcinoma is the most common type of tumour with predominance of high grade lesions.

Retinoblastoma tells the story of our health care system.

OBJECTIVE: To review cases of retinoblastoma. SETTING: Department of Pathology Aga Khan University Hospital Karachi. METHOD: Twenty-three specimens from cases of retinoblastoma received over a period of eight years were routinely processes and stained with haematoxylin and Eosin stain. Other stains were used for tuberculoses and melanin. Immunochemistry was resorted to in undifferentiated tumors. RESULTS: Over 60% cases of retinoblastoma were diagnosed after 5 years and nine cases showed involvement of optinerve. CONCLUSION: Late diagnosis of retinoblastoma effects the stage of the tumors and the prognosis.

Clinico-morphological pattern of intracranial tumors in children.

OBJECTIVE: The objective of present study was to observe the histopathological pattern of intracranial tumors in children (< 15 yrs) and to correlate the site of lesion along with the histological diagnosis. SETTING: The study included consecutive cases of intracranial tumors diagnosed in children (< 15 yrs.) in the section of histopathology at the Aga Khan University Hospital, Karachi during the period of three years. METHODS: The initial histological evaluation of these lesions was performed on H and E stained section of paraffin embedded tissue. Special stains and immunohistochemical analysis was done whenever indicated. RESULTS: During the study period, fifty-four cases of intracranial tumors were diagnosed in children. The age ranged from 1-1/2 years to 4 years with male to female ratio of 1.1:1. Astrocytoma comprised 39% of all intracranial tumors of childhood. Medulloblastoma (18.6%) ranked the second most prevalent brain tumor followed by empendymoma (13%), oligodendroglioma 7.5% while non-Hodgkin's lymphoma, primitive neuroblastoma 3.7% and ganglioglioma 3.7% while non-Hodgkin's lymphoma, primitive neuroectodermal tumors, mixed germ cell tumor, pineoblastoma, choroid plexus carcinoma and malignant meningioma constituted 1.8% each. CONCLUSION: Astrocytoma was the most common pediatric brain tumor. Medulloblastoma was more common in males while pilocytic astrocytoma was more frequent in females. Posterior cranial fossa was the most common site (43.5%) of pediatric brain tumors. Low grade astrocytoma was more prevalent in posterior cranial fossa as compared to high grade astrocytoma which was more frequent in the supratentorial region.

Diagnostic evaluation of fine needle aspiration cytology in the management of palpable breast lesions.

A total of 113 fine needle aspirates of the breast masses were evaluated in which the subsequent biopsy or mastectomy specimen were also available for histological examination. The age ranged from 16 to 80 years with a mean of 42 years. In benign conditions the mean age was 34.7 years while in malignant cases it was 48 years. The cytological diagnoses were compared with the histological results which revealed that the specificity and sensitivity of fine needle aspiration cytology in the palpable breast lesions was 86.1% and 89.2% respectively with a positive predictive value of 93% and efficiency of 88.2%. Similar statistics from other series in which the cytological results of breast lesions were compared with histological results, revealed almost same results which suggest that fine needle aspiration cytology is an effective and accurate technique for the diagnosis and management of palpable breast lumps.

Spinal cord compression: histologic spectrum of lesions.

Histologic diagnosis ultimately determines the prognosis and treatment of lesions causing spinal cord compression. Modern imaging techniques have revolutionized the procedure of localizing lesions presenting with signs and symptoms of spinal cord compression. As a result, these lesions are more accessible for fine needle aspiration and biopsy. A quick diagnosis is possible if cytologic preparation is made. Similarly, intraoperative frozen section facility not only provides rapid diagnosis, but also offers opportunity of appropriate management decision there and then. Histology in many cases needs help of special stains and immunocytochemistry. This study looks at the histologic spectrum of these lesions, gender distribution and age range in Pakistani population.

Barrett's oesophagus and Helicobacter pylori.

In order to demonstrate the presence of Helicobacter pylori in the metaplastic epithelium of Barrett's oesophagus and to evaluate its possible association with this entity, we examined 29 cases of Barrett's oesophagus where concomitant antral biopsies were also available. These cases were compared with an equal number of age and sex matched controls of uncomplicated reflux oesophagitis. H. pylori was present in 11 of 29 cases of Barrett's oesophagus (38%). No increase in the frequency of H. pylori antral gastritis was found in patients of Barrett's oesophagus compared to the control group of uncomplicated reflux oesophagitis. The positivity of Barrett's oesophagus for H. pylori correlated with the presence of H. pylori antral gastritis (P < 0.05), although in two cases of H. pylori-positive Barrett's oesophagus antral biopsies were negative for H. pylori. No difference was found in the severity of inflammatory and dysplastic changes of H. pylori-positive and H. pylori-negative Barrett's oesophagus. Presence of H. pylori does not seem to alter the natural history of Barrett's oesophagus.

Intraoperative frozen section consultation: an analysis of accuracy in a teaching hospital.

This is a retrospective quality assurance study of all frozen sections done at The Aga Khan University Hospital during a six year period (1986 to 1991). There were 1,031 frozen sections out of a cumulative total of 42,985 surgical specimens (2.39%). Nine hundred and severity-six (94.66%) were concordant. In 92 (8.9%) fresh specimens were brought from other hospitals of Karachi, in 37 cases (3.58%) the diagnosis was deferred till the evaluation of permanent paraffin sections and 18 (1.74%) were discordant with 7 (0.67%) false positive and 11 (1.06%) false negative. Among the discordant cases, 9 were attributed to misinterpretation, 7 due to sampling errors and 2 due to technical reasons. Some of these errors might have been avoided, but appear to be an irreducible minimum.