Louis Tsun-cheung Chow

Autonomic innervation of the human cardiac conduction system: changes from infancy to senility--an immunohistochemical and histochemical analysis.

In order to study the changes in the pattern of autonomic innervation of the human cardiac conduction system in relation to age, the innervation of the conduction system of 24 human hearts (the age of the individuals ranged from newborn to 80 years), freshly obtained at autopsy, was evaluated by a combination of immunofluorescence and histochemical techniques. The pattern of distribution and density of nerves exhibiting immunoreactivity against protein gene product 9.5 (PGP), a general neural marker, dopamine β‐hydroxylase (DBH) and tyrosine hydroxylase (TH), indicators for presumptive sympathetic neural tissue, and those demonstrating positive acetylcholinesterase (AChE) activity, were studied. All these nerves showed a similar pattern of distribution and developmental changes. The density of innervation, assessed semiquantitatively, was highest in the sinus node, and exhibited a decreasing gradient through the atrioventricular node, penetrating and branching bundle, to the bundle branches. Other than a paucity of those showing AChE activity, nerves were present in substantial quantities in infancy. They then increased in density to a maximum in childhood, at which time the adult pattern was achieved and then gradually decreased in density in the elders to a level similar to or slightly less than that in infancy. In contrast, only scattered AChE‐positive nerves were found in the sinus and atrioventricular nodes, but were absent from the bundle branches of the infant heart, whereas these conduction tissues themselves possessing a substantial amount of pseudocholinesterase. During maturation into adulthood, however, the conduction tissues gradually lost their content of pseudocholinesterase but acquired a rich supply of AChE‐positive nerves, comparable in density to those of DBH and TH nerves. The decline in density of AChE‐positive nerves in the conduction tissues in the elders was also similar to those of DBH and TH nerves. Our findings of initial sympathetic dominance in the neural supply to the human cardiac conduction system in infancy, and its gradual transition into a sympathetic and parasympathetic codominance in adulthood, correlate well with the physiologic alterations known to occur in cardiac rate during postnatal development. The finding of reduction in density of innervation of the conduction tissue with ageing is also in agreement with clinical and electrophysiological findings such as age‐associated reduction in cardiac response to parasympathetic stimulation. Finally, our findings also support the hypothesis that, in addition to the para‐arterial route, the parafascicular route of extension along the conduction tissue constitutes another pathway for the innervation of the conduction system of the human heart during development. Anat Rec 264:169–182, 2001.

Epithelioid hemangioendothelioma of the brain.

Epithelioid hemangioendothelioma is a recently described vascular neoplasm characterized by epithelioid tumor cells and borderline biologic behavior. Its four principal sites of occurrence are the soft tissue, liver, lung, and bone. We report a case of primary cerebral epithelioid hemangioendothelioma in a 4-month-old male infant. The tumor consisted of loose aggregates of epithelioid cells with a focal cordlike or bridging-branching pattern, supported in a fibromyxoid stroma. The tumor cells displayed frequent intracytoplasmic vacuoles. Immunohistochemically, the tumor cells showed positive staining for Ulex europaeus agglutinin, vimentin, and cytokeratin. The tumor pursued an indolent clinical course. The patient was alive 28 months after initial presentation, but he was left with a severe neurological deficit because of the location and growth of the tumor.

Biliary adenofibroma. A heretofore unrecognized benign biliary tumor of the liver

Benign biliary tumors of the liver are uncommon. In this report, we describe a distinctive biliary tumor of 7-cm diameter occurring in the right lobe of the liver of a 74-year-old Chinese woman. The lesion, characterized by a complex tubulocystic nonmucin secreting biliary epithelial and an abundant fibroblastic stromal components, is distinct from other well-recognized biliary lesions. A number of unusual features are focally present, namely, intraluminal bile concretions, apocrine-like epithelial change, acute inflammation, and granuloma. The tumor shows a striking resemblance to Meyenburgs complex (MC), but the large size of the lesion and the absence of any typical MC in the background liver are exceptional for the latter. Its expansile growth, possession of mitoses, and foci of epithelial tufting and cellular atypia favor a neoplastic process. Previous reported cases of adenomatous neoplastic transformation of MC are dissimilar. We therefore conclude that this is a hitherto unrecognized biliary tumor that may be yet another neoplastic form of MC and propose the designation biliary adenofibroma. The course appears benign, but malignant epithelial transformation may supervene if the lesion is left untreated.

Fatal massive upper respiratory tract haemorrhage: an unusual complication of localized amyloidosis of the larynx.

Localized amyloidosis of the larynx is usually described as a non-bleeding lesion. We report a patient with localized laryngeal amyloidosis who developed a massive upper respiratory tract haemorrhage and died. This potentially fatal complication of localized amyloidosis of the larynx merits recognition as the disease could be controlled in most instances by surgical excision of the amyloid deposit.

Extra-articular pigmented villonodular synovitis of the temporomandibular joint

Pigmented villonodular synovitis, a benign but locally destructive fibrohistiocytic proliferative lesion involving tendon sheaths, bursae and diarthrodial joints, is distinctly rare in the temporomandibular joint. We report one such case occurring in a 42-year-old housewife who presented with a progressively enlarging right zygomatic mass for six months. On exploration, an orange-brown firm mass, 5 x 3 x 2 cm, was seen adherent to the lateral aspect of the capsule of the right temporomandibular joint, and eroding into the inferior aspect of the right temporal bone and part of the mandibular condyle. The mass was completely excised. Pathological examination showed features typical of those of pigmented villonodular synovitis and the lesion was entirely extra-articular in location. The patient remained well with no evidence of local recurrence two years after operation. Review of the literature and careful analysis of the clinicopathological features showed that the vast majority of the reported cases of pigmented villonodular synovitis of the temporomandibular joint belonged to the extra-articular variant, which is associated with a more aggressive local infiltrative behaviour and higher rate of local recurrence than the localized type. The recommended treatment for this condition is therefore wide local excision, aiming to remove the lesion as completely as possible without producing severe disability for the patient.

Postmortem changes in the immunohistochemical demonstration of nerves in human ventricular myocardium

In order to delineate the effects of death on the immunofluorescence of autonomic nerves supplying the human ventricular myocardium, we studied percutaneous myocardial samples obtained postmortem from 5 individuals within 3 h of death. Subsequent samples were obtained daily from the same individuals up to a total of 5–11 d. The antibodies employed included those against protein gene product 9.5 to demonstrate nervous tissue, dopamine β‐hydroxylase and tyrosine hydroxylase to reveal catecholaminergic neural tissue and neuropeptide Y. An indirect immunofluorescence technique using the avidin‐biotin method was employed. The density of myocardial protein gene product 9.5 immunoreactive nerves declined on the 7th day, and became markedly diminished by the 11th day. Immunoreactive dopamine β‐hydroxylase nerves decreased on the 5th day, and were difficult to idenitify by the 9th day. The density of tyrosine hydroxylase and neuropeptide Y containing nerves rapidly diminished on the 3rd and 4th days, and became undetectable by the 7th and 8th days, respectively. The present results indicate that, depending on the type of antibodies used, immunohistochemical techniques can be used on human hearts obtained up to within 6 d of death to study cardiac innervation.

Isolated congenitally complete heart block attributable to combined nodoventricular and intraventricular discontinuity

Intraventricular together with atrial-axis and nodoventricular discontinuity, in which various parts of the conduction system are replaced by fibrous or fatty tissue, constitute the three major pathological categories of isolated congenitally complete heart block. Intraventricular discontinuity is distinctly rare, with only two previous cases reported in the literature, one of which was associated with a familial history of heart block. The cardiac conduction systems of two cases of isolated congenitally complete heart block were serially sectioned and analyzed histopathologically. The findings were correlated with the clinical features, in particular, the family histories and maternal serum anti-Ro antibodies. Both cases, a 9-day-old neonate and an 8-year-old schoolgirl, showed a combination of nodoventricular and intraventricular discontinuity, with absence of the atrioventricular penetrating bundle, the entire right, and the proximal portion of the left bundle branch. The branching bundle was absent in the first case and replaced by fatty tissue in the second. In contrast to the commoner atrial-axis discontinuity in which the atrioventricular node itself is usually replaced by fibrous or fatty tissue with variable involvement distally, the sinus node, and in particular, the atrioventricular node were normal in both of our cases. There was no family history in either case, whereas tests for the maternal serum anti-Ro antibody were positive in the first but negative in the second case. Intraventricular discontinuity as a cause of isolated congenitally complete heart block is very rare. In our cases, it co-existed with nodoventricular discontinuity. It can be sporadic, familial, or associated with positive maternal serum anti-Ro antibodies.

Co-existing pleomorphic and tubular basal cell adenomas of the parotid gland

We report a hitherto undescribed case of co-existence of a pleomorphic adenoma and a tubular basal cell adenoma affecting the superficial lobe of the left parotid gland of a 53-year-old man. The histology of the pleomorphic adenoma is also of interest in that the prominent adipose metaplasia of its myxoid stroma yielded an appearance reminiscent of myxoid lipoma. The tubular basal cell adenoma showed gross cystic change, and its solid portion consisted of closely packed tubules lined by double layers of cuboidal cells with little intervening stroma. Unlike Warthins tumour and membranous basal cell adenoma, both pleomorphic and tubular basal cell adenomas exhibit no propensity towards multicentricity or bilaterality. We, therefore, believe that their co-existence in the superficial lobe of the parotid gland of our patient is a mere coincidence rather than association.

Tuberculous aortitis with coronary ostial and left ventricular outflow obstruction: Unusual cause of sudden unexpected death

Tuberculous aortitis is a distinct, but uncommon, cause of thoracic and abdominal aortic aneurysms. We report an unusual case of tuberculous aortitis in a 12-year-old girl that resulted in her sudden death. The patient suffered from undiagnosed primary pulmonary tuberculosis affecting the apical region of her right lower lobe, with regional hilar lymphadenopathy. The granulomatous inflammatory process spread from the hilar lymph nodes to the aortic root, leading to tuberculous aortitis and the formation of an intraluminal tuberculoma just superior to the aortic valve. The tuberculoma also involved the ostia and proximal portions of both coronary arteries, resulting in obstruction of the coronary arteries in addition to the left ventricular outflow tract. The consequent myocardial fiber hypertrophy and interstitial fibrosis predisposed the patient to the development of fatal arrhythmias that most probably accounted for her sudden death.

Multinucleated myogenic giant cell formation: an unusual cellular reaction in acute myocardial infarction

We describe the presence of multinucleated myogenic giant cells in the heart of a patient with acute myocardial infarction. This represents an unusual myocardial cellular reaction, reminiscent of skeletal muscular regeneration following injury. The features that allow its differentiation from idiopathic giant cell myocarditis are discussed.