Wai Ming Yap

Ductal carcinoma in situ with spindle cells: a potential diagnostic pitfall in the evaluation of breast lesions

Aims : To evaluate the morphological features of 11 cases of breast ductal carcinoma in situ (DCIS) with spindle cells and to propose an approach to distinguish it from benign mimics. The association with neuroendocrine differentiation was also investigated.

Langerhans Cell Histiocytosis Involving the Thyroid and Parathyroid Glands

Langerhans cell histiocytosis (LCH) is a rare illness, and the disease afflicting the thyroid gland is very uncommon, even in the presence of multisystem involvement. In this report, we document histologically, for the first time, concurrent involvement of the thyroid and parathyroid glands by LCH. A young Chinese woman with a history of diabetes insipidus and hypogonadism underwent a total thyroidectomy for enlarged thyroid gland secondary to LCH causing airway obstruction. Microscopic examination of the excised specimen disclosed CD1a- and S-100–positive LCH cells involving the thyroid and parathyroid glands. In a patient with LCH affecting the thyroid gland, parathyroid gland disease should be suspected when the serum calcium levels are depressed in association with an inappropriate serum parathyroid hormone level, such as a normal parathyroid hormone level in this case.

Discovered on gastrointestinal stromal tumours 1 (DOG1) expression in non-gastrointestinal stromal tumour (non-GIST) neoplasms

Mertens F. FUS–CREB3 l2/l1-positive sarcomas show a specific gene expression profile with upregulation of CD24 and FOXL1. Clin. Cancer Res. 2011; 17; 2646–2656. 9. Doyle LA, Moller E, Dal Cin P, Fletcher CD, Mertens F, Hornick JL. MUC4 is a highly sensitive and specific marker for low-grade fibromyxoid sarcoma. Am. J. Surg. Pathol. 2011; 35; 733–741. 10. Doyle LA, Hornick JL. EWSR1 rearrangements in sclerosing epithelioid fibrosarcoma. Am. J. Surg. Pathol. 2013; 37; 1630– 1631. 11. Arbajian E, Puls F, Magnusson L et al. Recurrent EWSR1– CREB3 l1 gene fusions in sclerosing epithelioid fibrosarcoma. Am. J. Surg. Pathol. 2014; [Epub ahead of print].

Plasmablastic lymphoma affecting the lung and bone marrow with CD10 expression and t(8;14)(q24;q32) translocation.

Plasmablastic lymphoma is a rare variant of a diffuse, large B-cell lymphoma, which typically presents in the oral cavity in immunocompromised patients. In HIV positive patients, this tumor has a tendency to manifest in extramedullary sites. In this report, we document a rare instance in which this neoplasm besides affecting the bone marrow also involved the lung. In addition, the lymphoma in our case disclosed CD10 positivity on immunohistochemistry and t(8;14)(q24;q34) translocation on cytogenetic analysis, mimicking a Burkitt/atypical Burkitt lymphoma. The problems in diagnosis are discussed.

Tracheal carcinoma ex pleomorphic adenoma: a rare tumour with potential problems in diagnosis.

CLL with 17p deletion in our patient without EBV infection or prior fludarabine therapy. The pathogenesis in our patient is unclear and questions the use of the term Richter’s transformation for describing aggressive lymphomas arising in CLL ⁄ SLL that are molecularly distinct. The expression of CD5 in H-RS cells noted in our case has not been reported in previous cases of the HL variant of Richter’s transformation, although de novo HL has been known to express many T-cell antigens, CD2 and CD4 in particular. The B-cell genotype of H-RS cells and their clonal distinction from CLL ⁄ SLL cells suggest CD5 expression in the former is aberrant and cannot be used to infer a common clonal origin of the two neoplastic populations. In summary, our case adds to the literature on transformation of CLL ⁄ SLL to HL, which is a rare variant of Richter’s syndrome, and supports the hypothesis that the latter is a second neoplasm rather than clonal evolution of SLL.

Malignant perivascular epithelioid cell tumour of the fibula: a report and a short review of bone perivascular epithelioid cell tumour

Perivascular epithelioid cell tumour (PEComa) is a term applied to a family of mesenchymal tumours composed of varying proportions of spindle and epithelioid cell components associated with HMB-45 expression. PEComa rarely arises in the soft tissue, visceral organs, skin and bone. This report details an instance when a purely epithelioid PEComa arose from the right fibula of a 52-year-old Chinese woman without features of tuberous sclerosis complex. The excision specimen disclosed an epithelioid tumour with a nested pattern associated with areas of nuclear pleomorphism, mitotic activity, necrosis and vascular invasion in addition to HMB-45 expression on immunohistochemistry. To the best of the authors’ knowledge, this represents the first case of a histologically malignant PEComa of the bone. A short review of primary bone PEComas and potential problems in diagnosis is presented.

Diagnosis of adenoid cystic carcinoma of the lung by bronchial brushing: a case report.

BACKGROUND A diagnosis of pulmonary adenoid cystic carcinoma on exfoliative cytology specimen is very uncommon. The diagnostic cytologic material typically is obtained following a tissue biopsy. No previous report of the diagnosis has been made on bronchial brushing cytologic material when the procedure preceded a tissue biopsy. CASE A 44-year-old man who used to smoke cigarettes and was otherwise well complained of persistent cough for the past 6 months. A chest radiograph revealed a mass lesion in the left hilum. Computed tomography of the chest disclosed an irregular and spiculated soft tissue mass in the left apical anterior segment. Bronchial brushing via bronchoscope was performed, revealing carcinoma cells consistent with an adenoid cystic carcinoma on cytology. A bronchial biopsy and subsequent left upper lobectomy were performed, confirming the diagnosis of adenoid cystic carcinoma of the lung associated with tumor extension to the epithelial surface. CONCLUSION A diagnosis of bronchial adenoid cystic carcinoma is possible on bronchial brushing. However, as a method in exfoliative cytology, the usefulness of bronchial brushing in diagnosing this tumor is limited by the neoplasms proximity to the mucosal surface and whether the mucosa has been breached.

Solitary Fibrous Tumor of the Adrenal Gland with Unusual Immunophenotype: A Potential Diagnostic Problem and a Brief Review of Endocrine Organ Solitary Fibrous Tumor

Solitary fibrous tumor was initially thought to be a pleura-based tumor. However, over the last two decades, its involvement in a variety of extrapleural sites gained recognition. Nonetheless, a primary involvement of the endocrine organs is rare, and in this report, we detail an instance where the tumor affected the adrenal gland of a 71-year-old Arab man. On histology, besides the typical morphologic features seen in solitary fibrous tumor, the neoplasm also exhibited unusual features on immunohistochemistry such as positive staining for cytokeratin AE1/3 and calponin in conjunction with diffuse expression for S-100. The genetic tests for t(X:18) as seen in synovial sarcoma were negative, and the overall histological appearance favored a diagnosis of solitary fibrous tumor. To the best of our knowledge, this report represents the fifth case of a solitary fibrous tumor primarily occurring in the adrenal gland. The differential diagnoses of this neoplasm in our case and a brief summary of solitary fibrous tumor primarily involving the various endocrine organs are presented.

Proximal type epithelioid sarcoma arising in the base of the skull: a diagnostic challenge

Epithelioid sarcoma (ES) has been described in many sites1 and classical and proximal variants of ES display characteristic loss of INI1 expression.2 We detail, for what is believed to be the first time, a primary ES of the base of skull for which, because of extensive local disease, specific origin from dura or bone3 could not be determined. A 55-year-old Malay man presented with a 3-month history of epistaxis and visual disturbances. MRI scan revealed a large intracranial extra-axial lobulated mass measuring 7.0×6.1×7.3 cm with extension into the anterior cranial fossa, left posterior choana and left ethmoid sinus, suggesting a meningioma. The patient underwent tumour resection during which part of the skull base and small part of the left frontal lobe were removed. Intra-operatively, the lesion was extra-axial and remote from the normal appearing pituitary gland and suprasellar region. Postoperatively, a thorough physical examination, oesophago-gastro-duodenoscope and CT scan of the thorax, abdomen and pelvis failed to detect a primary tumour elsewhere. A repeat MRI of the brain and spine 1 month post surgery …

Cytological features of the native pineal gland in intraoperative squash preparations

The pineal gland, also known as the conarium, is one of the six circumventricular organs of the central nervous system. It has a location in the midline within the anterior quadrigeminal cistern, and lies above the superior colliculi, at the posterior recesses of the third ventricle. The pineal gland has unique histology among central nervous system tissues. It consists of prominent lobules surrounded by connective tissue septa. The pineocytes within the lobules form sheets within a fibrillary background, punctuated by distinctive pineocytic rosettes with central fibrillary cores. A population of astrocytes forms a loose network among the pineocytes. The pineocytes demonstrate immunoperoxidase expression of synaptophysin and neurofilament protein, while the supporting astrocytes are positive for glial fibrillary acid protein and S100 protein. Ultrastructural analyses of pineocytes have revealed morphological evidence of neurosensory differentiation by the presence of vesicle-crowned rodlets, fibrous filaments and paired twisted filaments, and also of neuroendocrine differentiation with dense core granules. After puberty, mineralized concretions known as corpora arenacea (or brain sand) become present and accrue with age. This is accompanied by gliosis and cystic change which gradually replace the cellular pineocytic population. Since the discovery of melatonin more than half a century ago, great strides have been made in characterization of the structure and function of the pineal gland. However to date, the cytological features of the normal pineal gland, as seen in intraoperative squash preparations has not been well illustrated in the literature. Intraoperative smear cytology using the technique of squash preparations is very commonly practiced in surgical neuropathology. This method provides superior morphological preservation in the neurosurgical setting where biopsies are often limited in size and the tissue is particularly vulnerable to freezing artefact. Unfortunately, the smear cytology features of the pineal gland are not familiar to many surgical pathologists, perhaps due to the relative rarity of lesions involving the pineal area, and the small size of the gland, rendering it readily overrun and destroyed by aggressive neoplasms. As lesions of the pineal region are being increasingly targeted by stereotactic biopsies and submitted for intraoperative diagnosis, knowledge of the cytological features of the normal pineal gland as encountered in the intraoperative setting is of importance. An ability to distinguish normal pineal tissue from lesional tissue is pivotal in intraoperative management; the finding of normal tissue prompts further surgical sampling to identify the actual lesion under the same anesthetic procedure. In this report, we describe the features of the native pineal gland on intraoperative squash preparation, as fortuitously encountered in a biopsy of a pineal lesion in a young female. The intraoperative smears were moderately cellular with cohesive clumps of cells within a fibrillary background. Peripheral areas of cellular discohesion were seen (Fig. C-1). The cells (pineocytes) formed sheets and rosettes with Department of Pathology, Tan Tock Seng Hospital, 11 Jalan Tan Tock Seng, Singapore, Singapore Department of Neurosurgery, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore, Singapore *Correspondence to: Khoon Leong Chuah, M.B.B.S., F.R.C.P.A., Department of Pathology, Tan Tock Seng Hospital, 11 Jalan, Tan Tock Seng, Singapore 308433, Singapore. E-mail: gzzckl@singnet.com.sg Received 3 January 2010; Accepted 29 January 2010 DOI 10.1002/dc.21373 Published online 14 May 2010 in Wiley Online Library (wileyonlinelibrary.com).