Schwannoma is a rare tumour in the liver. It is likely to arise from the hepatobiliary nerves among the hepatic plexus in the liver hilum as well as interlobular connective tissues and hepatic arteries. To the best of our knowledge, no prior publications have reported cases in Hong Kong.

We report the case of a 64-year-old man with a history of nasopharyngeal carcinoma and colon carcinoma and a new liver lesion detected on follow-up imaging for surveillance in 2018 following detection of a slightly elevated serum carcinoembryonic antigen level (4.7 μg/L). Alpha fetoprotein level was within the normal range (3.9 μg/L). Liver function tests were normal and he was asymptomatic with no history of neurofibromatosis.

Triphasic contrast computed tomography (CT) of the liver revealed a 5.2-cm ovoid hypodense lesion with heterogeneous enhancement in the caudate lobe of the liver (Fig 1). No washout of contrast was evident in the portal venous or delayed phases. Fluorodeoxyglucose-18 positron emission tomography–CT showed a moderately hypermetabolic lesion at the caudate lobe with a maximum standardised update value of 5.8 (Fig 2).

Surgical resection of the lesion was performed (Fig 3). Pathology showed a schwannoma and degenerative changes. Histological examination revealed an encapsulated tumour consisting of highly ordered Antoni type A and B areas (Fig 4). Immunohistochemical analysis showed the tumour cells to be diffusely positive for S100, consistent with neural differentiation (Fig 4). HerPar1, a mitochondrial antigen of hepatocytes, was negative. The CD34, a cell surface glycoprotein that is positive in gastrointestinal stromal tumour, was also negative.

Schwannoma is most commonly found in the limbs and the head and neck region. A fifth of cases shows association with neurofibromatosis type 1. The mediastinum and retroperitoneum are other possible sites. It is uncommon in the gastrointestinal tract and extremely rare in the liver.1 It was first reported in 1978 by Pereira et al.2 A literature search through PubMed and MEDLINE revealed 32 reported cases. No cases have been published in Hong Kong.

The origin of hepatic schwannoma is the hepatobiliary nerves among the hepatic plexus in the liver hilum as well as interlobular connective tissues and the hepatic arteries.1 3 They are usually well-encapsulated and grow very slowly, usually smaller than 5 cm at the time of diagnosis. Larger schwannomas may undergo secondary degeneration with consequent pseudocystic regression, haemorrhage, and calcification. Malignant transformation is very rare.3

Pathologically, a schwannoma is an encapsulated tumour that arises within the nerve sheaths. It consists of a highly ordered cellular component (Antoni type A area) characterised by spindle cells with twisted nuclei arranged in short bundles, and a hypocellular area in a loose myxoid stroma (Antoni type B area) that comprises a loose meshwork of gelatinous and microcystic tissue.4

On imaging, hepatic schwannoma is usually well circumscribed with various signal characteristics, depending on the distribution of Antoni A and Antoni B areas.1 It is commonly of low density with heterogeneous enhancement on CT, hypointense on T1-weighted, and hyperintense on T2-weighted magnetic resonance imaging.5 There have also been reports of malignant tumours but there are no distinct radiological features that differentiate them from benign tumours.3 A hepatic schwannoma may be fluorodeoxyglucose-avid depending on inflammatory activity and cellularity. Fluorodeoxyglucose-18 positron emission tomography–CT alone may enable differentiation of a schwannoma from malignant lesions of the liver.1

Hepatic schwannoma is an extremely rare tumour and preoperative diagnosis with imaging is challenging. Biopsy or surgical resection is usually required for definitive diagnosis.

Concept or design: All authors.
Acquisition of data: HL Tsui and CH Lau.
Analysis or interpretation of data: HL Tsui, SM Yu, and CH Lau.
Drafting of the manuscript: HL Tsui, SM Yu, and CH Lau.
Critical revision of the manuscript for important intellectual content: All authors.

All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

This study is approved by the cluster Research Ethics Committee (Ref KC/KE-19-0247/ER-3). Written patient consent was also obtained.

1. Hayashi M, Takeshita A, Yamamoto K, Tanigawa N. Primary hepatic benign schwannoma. World J Gastrointest Surg 2012;4:73-8. Crossref

2. Pereira Filho RA, Souza SA, Oliveira Filho JA. Primary neurilemmal tumour of the liver: case report. Arq Gastroenterol 1978;15:136-8.

3. Ozkan EE, Guldur M, Uzunkoy A. A case report of benign schwannoma of the liver. Intern Med 2010;49:1533-6. Crossref

4. Wan DL, Zhai ZL, Ren KW, Yang YC, Lin SZ, Zheng SS. Hepatic schwannoma: a case report and an updated 40-year review of the literature yielding 30 cases. Mol Clin Oncol 2016;4:959-64. Crossref

5. Yamamoto M, Hasegawa K, Arita J, et al. Primary hepatic schwannoma: a case report. Int J Surg Case Rep 2016;29:146-50. Crossref

A 47-year-old male smoker with hypertension, diabetes mellitus, and hyperlipidaemia complained of right eye vision loss on waking. His best-corrected visual acuity was reduced to light perception only. Physical examination revealed anisocoria without ptosis and no extraocular movement deficit. The right eye pupil was larger than the left, and the difference was more obvious under a light environment. Direct and consensual pupil reflexes were both present but there was a marked right relative afferent pupillary defect. Slit lamp examination revealed normal anterior segments of the eyes, but a right pale optic disc without rim thinning, and a typical cherry-red spot over the right fovea surrounded by generalised whitened retina. Vessels were not tortuous and no emboli were seen nor retinal haemorrhage over different layers (Figs 1 and 2). Left eye posterior segment was normal. The patient also reported right-sided headache and left-sided numbness. Thorough physical examination revealed no other cranial nerve deficit or systemic focal neurological deficit. Temporal pulse was easily palpable and non-tender, and no carotid bruit was heard. The patient worked on a construction site and denied any trauma. He commenced hyperbaric oxygen therapy but no improvement was observed. Blood tests and brain imaging were all normal, but carotid Doppler showed significant obstruction >90% of the internal carotid artery, accounting for the absence of bruit. Computed tomography angiography confirmed dissection of a long segment of the right internal carotid artery (Figs 3 and 4), not amendable to stenting or bypass surgery. A diagnosis of ophthalmic artery occlusion was made and explained the ineffectiveness of hyperbaric oxygen therapy due to choroidal ischaemia. Symptomatic internal carotid artery dissection is a rare but major cause of young-onset stroke, itself uncommon.1 Neck trauma is a major aetiology, and there is a slight male predominance with mean age of onset in the 40s.2 Apart from the neurological signs and symptoms of stroke, the ophthalmological presentation of internal carotid artery dissection is more similar to that of painful Horner’s syndrome due to compression of the adjacent third-order sympathetic chain fibres; followed by cranial nerve palsy, caused by direct local compression or compromise of feeder vessels.3 Ophthalmic artery occlusion is rare. Computed tomography angiography has 80% sensitivity for diagnosis and patients need to be closely monitored for massive stroke that may occur weeks to months after first presentation.4 Hyperbaric oxygen therapy is indicated for central retinal artery occlusion, but not ophthalmic artery occlusion. It aims to reperfuse the ischaemic retina with oxygen by diffusion from the choroidal circulation, bypassing the obstructed retinal vasculature. The choroidal arteries are supplied by the posterior ciliary arteries that branch from the ophthalmic artery. If the ophthalmic artery is occluded, hyperbaric oxygen therapy has no means to tackle the compromised posterior ciliary vessels.5

In conclusion, vision loss due to internal carotid artery dissection is uncommon. Multidisciplinary care is essential.

Concept or design: SCL Au.
Acquisition of data: SCL Au.
Analysis or interpretation of data: SCL Au.
Drafting of the manuscript: SCL Au.
Critical revision of the manuscript for important intellectual content: All authors.

All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

This pictorial medicine received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

This study was conducted in accordance with the principles outlined in the Declaration of Helsinki. Relevant patient consent was obtained for the purpose of this case study.

1. Thanvi B, Munshi SK, Dawson SL, Robinson TG. Carotid and vertebral artery dissection syndromes. Postgrad Med J 2005;81:383-8. Crossref

2. Blum CA, Yaghi S. Cervical artery dissection: a review of the epidemiology, pathophysiology, treatment, and outcome. Arch Neurosci 2015;2:e26670. Crossref

3. Kasravi N, Leung A, Silver I, Burneo JG. Dissection of the internal carotid artery causing Horner syndrome and palsy of cranial nerve XII. CMAJ 2010;182:E373-7. Crossref

4. Borgman CJ. Horner syndrome secondary to internal carotid artery dissection after a short-distance endurance run: a case study and review. J Optom 2012;5:209-16. Crossref

5. Kim SH, Cha YS, Lee Y, Kim H, Yoon IN. Successful treatment of central retinal artery occlusion using hyperbaric oxygen therapy. Clin Exp Emerg Med 2018;5:278-81. Crossref

A 63-year-old Chinese man from Wuhan, China, presented to the emergency department of Princess Margaret Hospital, Hong Kong, in January 2020 with coryzal symptoms.

He was afebrile with unremarkable respiratory examination results. He was admitted to an isolation ward for further investigation. He subsequently developed a fluctuating fever up to 38.5°C after admission and passed loose stool intermittently. His oxygen saturation levels were normal throughout hospitalisation. Supportive treatment and empirical antibiotics (amoxicillin-clavulanate) were administered.

Coronavirus disease 2019 (COVID-19) was suspected, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection was confirmed the next day by throat swab and nasopharyngeal aspirate tests. Stool culture was negative for SARS-CoV-2 and other pathogens.

Blood test results revealed lymphopoenia (0.6 × 109/L). Total white blood cell count (4.4 × 10⁹/L), absolute neutrophil count (3.4 × 10⁹/L), monocyte count (0.3 × 10⁹/L), and eosinophil count (0.0 × 10⁹/L) were normal. Liver and renal function test results, C-reactive protein level, and serum calcium and phosphate levels were normal.

Daily portable chest radiographs over the next 5 days were unremarkable (Fig 1). Chest high-resolution computed tomography (HRCT) was performed to assess for pulmonary involvement. High-resolution computed tomography performed 6 days after admission (Fig 2) demonstrated a few patchy subpleural ground-glass opacities in both lungs. No other abnormalities were detected. Subsequent follow-up chest radiograph (Fig 3) remained clear.

The patient’s fever subsided 11 days after admission. No supplemental oxygen was required. Serial nasopharyngeal aspirate sample tests turned negative 22 days after admission. The patient was discharged from the hospital 27 days after admission.

The SARS-CoV-2 infection is diagnosed with reverse transcription polymerase chain reaction results of respiratory specimens.

Prior to availability of confirmatory microbiological test results, challenges exist in decision making for patients with suspected COVID-19.

We advocate that early HRCT should be considered in suspected cases to aid in clinico-radiological diagnosis of SARS-CoV-2 infection by demonstrating compatible radiological features, before microbiological confirmation has been established.

This can be especially beneficial if patients have negative preliminary virology or radiographic findings, as in the previously reported HRCT features in severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS),1 2 as well as recent reports on COVID-19 from China3 and Hong Kong.4

Findings on serial chest radiographs before and after HRCT remain occult without demonstrable airspace opacity, limiting its value in initial assessment, monitoring or exclusion of pulmonary involvement.

This is consistent with experience during the SARS epidemic that HRCT was useful for early radiological assessment for patients with negative chest radiographs.5

Our patient subsequently demonstrated a favourable outcome with recovery and did not require supplemental oxygen throughout hospitalisation.

Mirroring experiences in previous coronavirus outbreaks such as SARS and MERS, we believe that HRCT will likely play a key role in aiding diagnosis, assessing the extent of pulmonary involvement and risk in the current COVID-19 pandemic. Early HRCT can be beneficial in patients with obscure clinical presentation or negative preliminary virological or radiographic findings.

All authors contributed to the concept or design of the study, acquisition of the data, drafting of the manuscript, and critical revision of the manuscript for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

We would like to express our gratitude to the Infectious Disease Team and “dirty team” physicians of Princess Margaret Hospital, Hong Kong, for their professional patient care and invaluable contribution to the understanding of a novel disease.

This pictorial medicine paper received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

This study was approved by the Kowloon West Cluster Research Ethics Committee (Ref KW/EX-20-049(145-08)).

1. Koo HJ, Lim S, Choe J, Choi SH, Sung H, Do KH. Radiographic and CT features of viral pneumonia. Radiographics 2018;38:719-39. Crossref

2. Franquet T. Imaging of pulmonary viral pneumonia. Radiology 2011;260:18-39. Crossref

3. Lei J, Li J, Li X, Qi X. CT imaging of the 2019 novel coronavirus (2019-nCoV) pneumonia. Radiology 2020;295:18. Crossref

4. World Health Organization. Clinical management of severe acute respiratory infection when COVID-19 is suspected. Interim guidance. Available from: https:// www.who.int/publications-detail/clinical-management-of-severe-acute-respiratory-infection-when-novel-coronavirus-(ncov)-infection-is-suspected. Accessed 6 Feb 2020.

5. Hui JY, Hon TY, Yang MK, et al. High-resolution computed tomography is useful for early diagnosis of severe acute respiratory syndrome-associated coronavirus pneumonia in patients with normal chest radiographs. J Comput Assist Tomogr 2004;28:1-9. Crossref

Radiological imaging is now readily available in Hong Kong, in both the public and private sector. Imaging helps diagnose or screen for diseases, but can create noise or false alarms.1 Ophthalmology consultations are common in both in-patient and out-patient settings. Floaters, visual field defects, and abnormal incidental findings on computed tomography or magnetic resonance imaging (MRI) are all common reasons for consultations.2

In 2018, a 60-year-old man underwent an MRI scan for acoustic neuroma screening, which revealed an abnormal eyeball shape (Fig 1). Diligent consultation with an ophthalmologist was reassuring for both the physician and the patient. In December 2017, the patient had been referred to our eye department for visual disturbance and was diagnosed with right eye macula-on retinal detachment. He had no history of laser or other eye surgery, nor trauma to the eyes. The patient reported right eye floaters and loss of the inferior visual field. Fundus examinations found a large retinal U-shaped tear at the superior retina, with bullous retinal detachment over the right eye. There were also multiple small flat holes with lattice degeneration over the retina in the temporal and nasal aspect. Retinal detachment repair surgery with encircling band as scleral buckling, and intravitreal gas injection was done for the presence of multiple retinal holes.3 Given the patient’s older age, the presence of cataract, and perceived cataract progression with postoperative intravitreal gas,4 cataract extraction with intraocular lens insertion was also done in the same operation. These are all evidenced on the MRI scan contrasting the presence of a natural thickness lens over the left eye.

Retinal detachment surgery can be of external or internal approach to relieve the vitreous traction and flatten the retina. External approach can be localised or 360-degree encircling depending on the retinal status.

The formation of the pear-shaped eyeball was due to the buckling effect of the encircling band (Fig 2). With basic knowledge of normal organ shapes, all practitioners would be concerned by such a deformed organ on plain radiographs. Typically, intraocular tumours or eyeball ruptures are not regular nor symmetrical, except large ring melanoma of the ciliary body. The key to differentiating a genuine pathology from a congenital/postoperative variant lies heavily on clinical history.1 Operative implants usually appear regular, or even symmetrical on imaging.

All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

Concept or design: SCL Au.
Acquisition of data: SCL Au.
Analysis or interpretation of data: SCL Au.
Drafting of the manuscript: SCL Au.
Critical revision of the manuscript for important intellectual content: All authors.

All authors have disclosed no conflicts of interest.

This pictorial medicine paper received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

This study was conducted in accordance with the principles outlined in the Declaration of Helsinki. Relevant patient consent was obtained for the purpose of this case study.

1. Leslie A, Jones AJ, Goddard PR. The influence of clinical information on the reporting of CT by radiologists. Br J Radiol 2000;73:1052-5. Crossref

2. Carter K, Miller KM. Ophthalmology inpatient consultation. Ophthalmology 2001;108:1505-11. Crossref

3. Shanmugam PM, Ramanjulu R, Mishra KC, Sagar P. Novel techniques in scleral buckling. Indian J Ophthalmol 2018;66:909-15. Crossref

4. Thompson JT. The role of patient age and intraocular gases in cataract progression following vitrectomy for macular holes and epiretinal membranes. Trans Am Ophthalmol Soc 2003;101:485-98.

In January 2017, a 35-year-old woman was admitted to our hospital with insidious onset of upper abdominal pain. A computed tomography (CT) scan showed bilateral ovarian cysts with fat fluid level, calcifications, and Rokitansky protuberance, compatible with ovarian teratoma (Fig 1). Anti-dependent fatty pockets with soft tissue rim were found at the bilateral subphrenic space, likely representing reactive changes to spilt cyst content, which also explained the patient’s upper abdominal pain. The patient had stable vital signs and was therefore treated conservatively. Follow-up ultrasonography scan showed globular fatty locules on the liver surface, compatible with escaped fatty cyst content (Fig 2). Subsequently, the patient underwent bilateral ovarian cystectomy. Histology confirmed bilateral ovarian mature cystic teratoma. Intra-operatively, widespread flimsy adhesions and multiple sebum-like implants were seen in the peritoneal cavity, consistent with changes related to teratoma rupture. The peritoneal cavity was irrigated and her symptoms gradually subsided; however, follow-up CT showed mild interval enlargement of the fat-attenuated lesions (Fig 3).

Mature cystic teratomas (also known as dermoid cysts) are common ovarian germ cell neoplasms accounting up to 10% to 25% of all ovarian neoplasms.1 They are cystic tumours composed of well-differentiated derivations from at least two of the three germ cell layers. Tumours are bilateral in about 10% of cases. On ultrasonography, cystic teratoma commonly manifests as a cystic lesion with a densely echogenic tubercle projecting into the cystic lumen; or a diffusely or partially echogenic mass with posterior attenuation by sebaceous material and hair. Multiple thin echogenic bands caused by hair in cyst cavity can also been seen. Pure sebum within the cyst can be hypoechoic or anechoic, fluid-fluid level can result from sebum floating on aqueous fluid which appears more echogenic than the sebum layer. On CT, the diagnosis of mature cystic teratoma is rather straightforward; fat attenuation within a cyst is diagnostic of mature cystic teratoma. Teeth or other calcifications can be seen in 56% of cases.2

Spontaneous rupture is an uncommon complication of dermoid cysts owing to the presence of a thick capsule, and is only seen in 1% to 4% of cases.1 Acute peritonitis can result from sudden rupture of tumour contents as seen in the present case. Chronic granulomatous peritonitis is caused by chronically leaking teratoma and is characterised by multiple small white peritoneal implants and dense adhesions with variable ascites. Visualisation of fatty implants within the peritoneal cavity is diagnostic.3

The reported CT findings of granulomatous peritonitis or intraperitoneal rupture of teratoma are inconsistent.1 3 In one case, capsular fatty implants were seen in the dome of the liver, similar to the CT appearance in the present case. In other patients there can be a significant amount of intraperitoneal free fluid and an omental cake appearance mimicking peritoneal carcinomatosis.

Chronic granulomatous peritonitis is a potentially serious complication of ruptured dermoid cyst and can lead to bowel obstruction resulting from adhesion. Removal of cystic content and copious peritoneal lavage should be performed to prevent new adhesion and peritoneal granuloma, and can be a successful method for treating chemical peritonitis caused by ruptured ovarian teratoma.4 In the present case, progression of the right subphrenic fatty implant, possibly related to incomplete removal of the cystic content, resulted in chronic granulomatous peritonitis. The patient may have benefitted from further peritoneal lavage.

WL Wong contributed to acquisition of data. All authors contributed to concept or design, analysis or interpretation of data, drafting of the article, and critical revision for important intellectual content. All authors had full access to the data, contributed to the study, approved the final version for publication, and take responsibility for its accuracy and integrity.

All authors have disclosed no conflicts of interest.

This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

This study was approved by the Kowloon Central/Kowloon East Research Ethics Committee (Ref KC/KE-19-0158/ER-4). Informed consent was obtained from the patient.

1. Erbay G. Ruptured ovarian dermoid cyst mimicking peritoneal carcinomatosis: CT and MRI. J Clin Anal Med 2016;6:701-3.

2. Outwater EK, Siegelman ES, Hunt JL. Ovarian teratomas: tumor types and imaging characteristics. Radiographics 2001;21:475-90. Crossref

3. Fibus TF. Intraperitoneal rupture of a benign cystic ovarian teratoma: findings at CT and MR imaging. AJR Am J Roentgenol 2000;174:261-2. Crossref

4. Shamshirsaz AA, Shamshirsaz AA, Vibhaka JL, Broadwell C, Van Voorhis BJ. Laparoscopic management of chemical peritonitis caused by dermoid cyst spillage. JSLS 2011;15:403-5. Crossref