Patrick P L Lau

Queen Elizabeth Hospital, Hong Kong, Hong Kong

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Publications (13)33.73 Total impact

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    ABSTRACT: Plexiform fibromyxoma (plexiform angiomyxoid myofibroblastic tumor) is a rare benign mesenchymal tumor of stomach. The plexiform growth of bland-looking spindly cells in a richly vascularized fibromyxoid stroma is distinctive. The described cases are solid tumors associated with ulceration, with the patients presenting with symptoms related to the ulcer or mass effect of the tumor. We report an unusual case presenting as a fistulating abscess. A 42-year-old woman presented with abdominal pain, fever, and elevated white cell count. Computed tomography scan revealed a 12-cm cavitating mass in the gastric antrum, with fistulation to the gastric lumen through an ulcer. Histologic examination showed transmural involvement of the stomach by plexiform islands of fibromyxoid tumor with interspersed delicate capillaries. There was a pseudocyst-like component. The unusual presentation therefore broadens the clinical and pathologic spectrum of this rare tumor type.
    International Journal of Surgical Pathology 06/2013; · 0.76 Impact Factor
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    ABSTRACT: Low-grade fibromyxoid sarcoma (LGFMS) is an uncommon sarcoma with a deceptively bland-looking morphology that disguises its malignant clinical behavior. It shows distinctive chromosomal translocations resulting in fusion of FUS with the CREB3L2 gene in most cases and CREB3L1 in rare cases. Thus molecular studies are particularly helpful in the diagnosis of this bland-looking sarcoma. We report 2 cases of LGFMS serendipitously found to harbor a novel alternative EWSR1-CREB3L1 gene fusion, as confirmed by DNA sequencing of reverse transcriptase-polymerase chain reaction products and fluorescence in situ hybridization. One patient was a child who presented with a subcutaneous nodule on the lower leg, and the other was a middle-aged woman who had a mass lesion over the proximal thigh. Morphologically, one case showed a spindle cell tumor with hyalinization and giant rosettes, whereas the other showed classical histology of LGFMS with focal metaplastic bone formation. Immunostaining for MUC4 showed extensive positive staining. Our findings therefore expand the spectrum of gene fusions that characterize LGFMS and suggest that the EWSR1 gene may substitute for the function of FUS in gene fusions of sarcoma.
    The American journal of surgical pathology 05/2013; 37(5):734-8. · 4.06 Impact Factor
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    ABSTRACT: Reticular/microcystic schwannoma is a recently described morphologic variant of schwannoma that occurs predominantly in visceral organs, most commonly the gastrointestinal tract. This report describes a case occurring in the masticator space, accompanied by focal erosion of the orbital floor, clinically and radiologically worrisome for malignancy. The 26-year-old man presented with facial swelling for 3 month. The tumor shows a multinodular appearance, with dense lymphoplasmacytic infiltrates in the fibrous septa. The tumor nodules are composed of plump spindle cells disposed in a reticular pattern. The diagnosis is confirmed by strong positive staining for S100 protein. The differential diagnoses of reticular schwannoma in the soft tissues of head and neck region are different from those in the gastrointestinal tract.
    International Journal of Surgical Pathology 06/2012; · 0.76 Impact Factor
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    ABSTRACT: Myopericytoma is an uncommon, benign perivascular myoid cell tumor that occurs almost exclusively in somatic soft tissues. We report 2 cases occurring in patients with acquired immunodeficiency syndrome who show unusual clinical and biologic features. One patient presented with a bronchial mass and the other developed mass lesions of the tongue, vocal cord, and brain. Histologically, oval to plump spindly tumor cells with uniform nuclei and scanty cytoplasm formed sheets or cuffs around gaping or narrow vascular spaces. Focally, these areas merged into fascicles of more elongated cells with eosinophilic cytoplasm. The tumor cells were immunoreactive for actin but not desmin, and showed uniform labeling for Epstein-Barr virus (EBV) encoded RNAs on in-situ hybridization. Both patients were alive 5 years after incomplete excision of the lesions. In conjunction with another case reported in the literature, myopericytoma occurring in acquired immunodeficiency syndrome patients exhibits several features distinct from sporadic myopericytoma: presentation in anatomic sites other than somatic soft tissues, frequent presence of multifocal disease, and association with EBV. This tumor type therefore also broadens the spectrum of neoplasms associated with EBV.
    The American journal of surgical pathology 09/2009; 33(11):1666-72. · 4.06 Impact Factor
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    ABSTRACT: We conducted a 12-year retrospective review of vulvar basal cell carcinoma (BCC) in a Chinese population. Medical records and histopathologic reports were examined from 5 major Hospitals in Hong Kong to list all patients diagnosed with vulvar BCC. Clinical data and histologic materials were reviewed. Sixteen vulvar BCCs were diagnosed. Most of them were pigmented. They were removed by simple excision or wide local excision. All the carcinomas were identified in the reticular dermis. The predominant histologic pattern was nodular, which may be mistaken as adenoid cystic carcinoma. The high proportion of pigmented vulvar BCCs suggested that biopsy should be performed for any pigmented lesion in a Chinese patient. The BCCs are superficial and tissue-preserving treatment approach is recommended. The tumor depth estimation is difficult and intraoperative frozen section consultation may be helpful. Formal histopathologic assessment should be used to reach an objective diagnosis.
    American journal of obstetrics and gynecology 03/2009; 200(5):514.e1-5. · 3.28 Impact Factor
  • Patrick P L Lau, Alexander C L Chan, M H Tsui
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    ABSTRACT: To study the cytological features of breast lesions associated with hydrophilic polyacrylamide gel (PAAG) injection augmentation mammoplasty and to determine the specific diagnostic features. Fine needle aspiration (FNA) cytology smears from 14 patients who presented with breast lump and a clinical history of PAAG injection were reviewed. The staining properties of the PAAG material in Papanicolaou (Pap), Haematoxylin and Eosin (H&E) and Diff-Quik stains, as well as the cellular background, were studied. Cell blocks were also studied with H&E, periodic acid-Schiff (PAS), periodic acid-Schiff with diastase digestion (PASD) and mucicarmine (MC) stains. PAAG was stained consistently pinkish with a homogenous smooth texture on H&E (100%), polychromasia on Pap (100%) and magenta violet with bubbly vacuoles on Diff-Quik (100%). Half (7) of the cases showed sharp borders. The presence of foreign body type giant cells with histiocytes (5 cases, 36%) and scanty clusters of benign ductal cells (4 cases, 29%) were seen in the background of a minority of the cases. PAAG was represented by blocks of homogenous grey-purplish acellular material with a sharp border on cell block sections, which were negative for PAS, PASD and MC. PAAG shows a consistent staining pattern in various common cytological staining preparations. Blocks of acellular gelatinous material, stained homogenous pinkish on H&E, polychromasia on Pap and magenta violet with bubbly vacuoles on Diff-Quik, are the reliable cytological features of PAAG.
    Pathology 01/2009; 41(5):443-7. · 2.66 Impact Factor
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    ABSTRACT: Chordoid meningioma is a rare meningioma variant characterised by epithelioid cord-like tumour cells in a myxoid stroma. It is classified as grade II (World Health Organization) tumours, as they have a tendency to behave more aggressively than traditional meningiomas and have a greater likelihood of recurrence. To report the features of intraoperative imprint smears of five cases of chordoid meningioma. The intraoperative squash smears were reviewed for cellularity, cellular atypia, mitotic figure, cytoplasmic vacuolation, intranuclear inclusion, presence of a cohesive cord of tumour cells, whorl-like structure, psammoma bodies, chronic inflammatory cells (lymphocytes and plasma cells), background mucin and necrosis. All cases were of moderate to high cellularity, with cohesive cords of bland tumour cells possessing uniformly round nuclei with smooth nuclear outline, stippled chromatin and small nucleoli, with cytoplasmic vacuolation and chronic inflammatory cells in the background. Intranuclear inclusions (80%) and whorl-like structures (60%) were also common. Necrotic background, psammoma bodies or mitotic figures were consistently absent. The cytological features of chordoid mengiomas are distinctive, and intraoperative imprint diagnosis is feasible.
    Journal of Clinical Pathology 10/2007; 60(9):1024-8. · 2.44 Impact Factor
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    ABSTRACT: To determine the pathognomonic diagnostic cytological features of invasive micropapillary carcinoma of the breast which is a poor prognostic subtype of infiltrating ductal carcinoma. A series of 20 histologically proven tumours were reviewed retrospectively to evaluate the various cytological features, including tumour morules, isolated malignant cells, staghorn epithelial structures, mucinous background and apocrine metaplasia. Tumour morules formation and isolated malignant cells were the two most reliable and constant cytological features, being present in 75% (15/20 cases) of cases. Staghorn epithelial structures were present in 35% (7 cases). Mucinous background (2 cases, 10%) and apocrine metaplasia (4 cases, 20%) of the tumour cells were seen in a few cases only and did not appear very helpful. Tumour morules formation, isolated malignant cells and staghorn epithelial structures are the most reliable cytological features, and the presence of these should raise suspicion of invasive micropapillary carcinoma.
    Pathology 09/2007; 39(4):401-5. · 2.66 Impact Factor
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    ABSTRACT: Metaplastic carcinoma of the breast encompasses a heterogeneous group of tumours with variable components of sarcomatoid, squamous or poorly differentiated carcinomas. To review a series of 19 cytological preparations of metaplastic carcinomas to assess diagnostic cytological features. 17 cases of fine-needle aspirates of histologically proven metaplastic carcinomas (4 monophasic spindle cell carcinomas, 4 squamous cell carcinomas and 11 biphasic tumours) were reviewed, with an emphasis on the presence of poorly differentiated carcinoma, squamous cell carcinoma, atypical spindle cells, benign stromal fragments and necrosis. All cases were diagnosed as malignant, with 68% of cases showing moderate to high cellularity, and 47% showing necrosis. If the tumours were analysed according to the constituting components histologically, 7, 15 and 8 cases, respectively, possess poorly differentiated carcinoma cells, sarcomatoid malignant cells and squamous carcinoma cells, whereas these components were cytologically identified in 11, 10 and 7 cases, respectively. Dual tumour populations were identified in only 5 of the 11 biphasic carcinomas in the cytological preparations; and the stromal material was cytologically identified in the only case with chondroid stroma. Identification of metaplastic carcinoma in cytology remains problematic. There seems to be morphological overlap between various components. The identification of dual components, unequivocal squamous carcinoma cells and chondroid stroma is helpful for diagnosis, but it is uncommon. The presence of poorly differentiated carcinoma cells with a suggestion of focal spindle morphology is another clue to the suggestion of metaplastic carcinoma.
    Journal of Clinical Pathology 06/2007; 60(5):529-33. · 2.44 Impact Factor
  • Pathology 11/2006; 38(5):458-61. · 2.66 Impact Factor
  • Patrick P L Lau, Philip C W Lui
    Pathology 11/2006; 38(5):456-8. · 2.66 Impact Factor
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    ABSTRACT: An abstract is unavailable. This article is available as HTML full text and PDF.
    Pathology 05/2006; 38(2):186-9. · 2.66 Impact Factor
  • Pathology 03/2006; 38(1):78-80. · 2.66 Impact Factor