Local molecular analysis of indeterminate thyroid nodules

BACKGROUND

Thyroid nodules are common but only a minority are malignant. Molecular testing can assist in helping determine whether indeterminate nodules are suspicious for malignancy or benign. The objective of the study was to determine if the analysis of mutations (BRAF, NRAS, KRAS and HRAS) using readily available molecular techniques can help better classify indeterminate thyroid nodules.

METHODS

A retrospective cohort of consecutive patients undergoing diagnostic thyroid surgery were analyzed for the presence or absence of specific mutations known to be associated with thyroid malignancy in FNA samples. Markers chosen were BRAF, NRAS, KRAS and HRAS. All were locally available and currently in use at our centre for other clinical indications. Results from the molecular analysis were then compared to the histopathology from thyroidectomy specimens to determine the sensitivity and specificity of these molecular techniques to classify indeterminate thyroid nodules.

RESULTS

Sixty consecutive patients with indeterminate FNAs were recruited. Twenty-three patients had malignant tumors while 37 specimens were benign. Multiple different mutations were identified in the FNA samples. Overall 18 cases had a positive mutation (10 malignant and 8 benign). The sensitivity of BRAF, HRAS, KRAS, and NRAS was 8.7, 8.7, 8.7, and 17.4 respectively while the specificity was100, 83.7, 100 and 94.6.

CONCLUSION

While molecular analysis remains promising, it requires further refinement. Several markers showed promise as good "rule-in" tests.

Amelanotic Melanoma Presenting with Plasmacytoid Morphology and BRAF V600 Mutation

Plasmacytoid melanoma is an unusual variant of malignant melanoma. The plasmacytoid morphology can be found in a variety of other malignancies including carcinomas, plasma cell neoplasms, lymphoproliferative disorders, and sarcomas. The authors report a rare case of plasmacytoid amelanotic malignant melanoma in a 78-year-old man presenting with an enlarging palpable, erythematous mass on his left posterior shoulder. A fine needle aspirate showed atypical findings with single amelanotic cells with high nuclear to cytoplasmic ratio, mono- and multi-nucleation with prominent nucleoli and intranuclear inclusions. Review of the excision and immunohistochemical analysis revealed the malignant plasmacytoid cells stained with vimentin, S-100, HMB-45, and other staining patterns consistent with melanoma. Initial evaluation was negative for other sites of disease. However, 4 months later, the patient was noted to have metastatic disease to his lungs and liver. Given that the tumor was noted to be BRAF V600R mutated, the patient was started on single agent dabrafenib. The plasmacytoid morphology can be found in a variety of malignancies. Melanoma should be considered in the differential diagnosis of any malignancy presenting with plasmacytoid features.

Radiologic and Histopathologic Features of Calcifying Pseudoneoplasm of the Neural Axis

Aim

To describe the radiologic and corresponding histopathologic features of calcifying pseudoneoplasms of the neural axis.

Methods

Two cases of calcifying pseudoneoplasm of the neural axis were retrospectively reviewed. The first case was documented in a 64-year-old woman, who presented with lower back pain with radiation to her left leg. The second case was documented in a 70-year-old man, who presented with headaches. Medical records, radiologic and histologic findings, and related literature were reviewed.

Results

In the first case, imaging of the lumbar spine revealed a 3.8 × 2.2-cm calcified lesion at the level of vertebrae L5 and S1. A subsequent excision exposed an extradural lesion at L5. Histopathologic examination showed amorphous and granular calcifying material with occasional fibrohistiocytic and giant cell reaction, consistent with calcifying pseudoneoplasm of the neural axis. In the second case, imaging of the head revealed a 2.4 × 2.6-cm well-circumscribed, lobulated, calcified lesion within the basal frontal lobe. Subsequent resection exposed an intradural mass with a nodular arrangement of amorphous and granular calcifying material associated with fibrohistiocytic and giant cell reaction. Both patients had a favorable postoperative course and failed to show any clinical or radiologic sign of recurrence.

Conclusion

Calcifying pseudoneoplasm of the neural axis is an uncommon condition with an excellent prognosis but is often misdiagnosed due to its nonspecific clinical presentation and varied findings on radiology.

Pleura nodosum: fetal squamous debris in an unusual location

We present a pathologic-radiologic case of a fetus with a right extralobar bronchopulmonary sequestration that required intervention in the form of a thoraco-amniotic shunt for management of a right pleural effusion. The intervention was successful in reducing the pleural effusion and the infant was born at 39 weeks gestational age but required some respiratory support for the 1st day of life. The pulmonary sequestration was excised on day 7 of life and demonstrated several small nodules on its pleural surface. Histologic examination demonstrated that the nodules consisted of granulomatous plaques containing squamous epithelium and hairs. The nodules are similar to those described in amnion nodosum, when the amniotic membrane incorporates fetal skin within the superficial tissue layers of the placenta in cases of oligohydramnios. To our knowledge, this is the 1st reported case of nodules containing amniotic fetal squamous debris to occur on lung visceral pleura.

Sudden cardiac death: a modern pathology approach to hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy is one of the most common causes of sudden cardiac death among young adults and adolescents. Unfortunately, the first manifestation of the condition may be sudden death during exertion, such as sporting activities. Other clinical symptoms include exertional dyspnea, angina, and syncope. Postmortem examination often reveals asymmetrical septal thickening and mural plaque formation in the left ventricular outflow tract. Histologic analysis shows cardiac myocyte hypertrophy, myofiber disarray, and interstitial and replacement fibrosis. Molecular analysis for known genetic abnormalities is essential to genetic counseling of living relatives of decedents to assess and reduce the risk of sudden cardiac death from hypertrophic cardiomyopathy.

Retrospective Analysis of Oxycodone- and Cocaine-Related Deaths in Southwestern Ontario during 2003–2010

Oxycodone hydrochloride is a potent semisynthetic opioid analgesic with a primary role in moderate to severe chronic pain management. It was approved by Health Canada in 1996 for that purpose and added to the Ontario provincial drug formulary in 2000. Increases in oxycodone abuse and oxycodone-related deaths have been noted in both Canada and the USA since oxycodone's introduction to the pharmaceutical market. A retrospective analysis was conducted, reviewing all of the medicolegal autopsies performed at a regional Ontario Forensic Pathology Unit, from 2003–2010. All cases that listed oxycodone and/or cocaine as cause of death were reviewed to ascertain trends in demographic data, preexisting prescription medication use, and concomitant drug use. Cocaine-related deaths were analyzed in order to contextualize oxycodone-related deaths in the setting of drug abuse. Oxycodone-related deaths were observed to increase from 2003–2010 and surpassed cocaine-related deaths in 2010. The proportion of female to male oxycodone-related deaths did not statistically differ during the study years. The proportion of female deaths was constant over the study period, however, male deaths showed a statistically significant increase by 23% from 2009–2010. Females were more likely to die from oxycodone rather than cocaine use, and the converse was seen in males. Among all oxycodone-related deaths over half of the decedents (53%) had a prescription for oxycodone. Oxycodone was also more likely to be reported with polysubstance use. This study illustrates how an abused prescription analgesic can be an ever-increasing burden on society even ten years after its release onto the market.

Femoral artery pseudoaneurysm due to Candida albicans in an injection drug user

Candida arteritis is an uncommon condition but important to recognize due to the risk of significant morbidity and the difficulty in management of the enduring fungal infection. The authors report a rare case of a man with a femoral artery pseudoaneurysm with persistent Candida albicans infection, as a complication of infective endocarditis. The 23-year-old man, with a history of chronic intravenous drug use and Type I diabetes mellitus, presented with left groin pain, paresthesia of his left foot, and a pulsatile mass in the inguinal region. On imaging, he was found to have a pseudoaneurysm of the left common femoral artery, which later ruptured. Further investigation revealed vegetations on the mitral and aortic valves as well. Initial blood cultures were negative. He underwent multiple surgical interventions including replacement of the mitral and aortic valves and resection of the left common femoral artery with autogenous revascularization. In addition, he was commenced on intravenous antifungal therapy. Postoperatively, he continued to experience significant pain in the left groin and had two episodes of rerupture of the femoral artery that was consequently surgically repaired. Histological examination of the resected valves revealed vegetations with a mixture of fungal elements and bacterial cocci. The femoral artery resection specimens revealed evidence of infectious arteritis and the presence and persistence of C. albicans organisms in subsequent specimens. This case highlights the importance of an accurate diagnosis and aggressive management of fungal mycotic aneurysms in at-risk populations.

Acute Fatal Peritonitis: A New Organism for Consideration

A 40-year-old man died suddenly and unexpectedly at home. His comorbid conditions included central diabetes insipidus, obesity, and hypertension. Autopsy revealed acute and chronic pancreatitis with an abscess and associated purulent peritonitis. Peritoneal fluid cultures grew Raoultella planticola and a light growth of Candida albicans. The organism isolated, R. planticola, is a waterborne bacterium with limited previous clinical isolates causing morbidity but no previously described mortality. Vitreous humor analysis demonstrated concomitant acute water intoxication complicating the decedent's diabetes insipidus. Discussion includes a review of the literature with a description of the eight previous cases of human infection with R. planticola, a recently described organism that was previously in the genus Klebsiella. The proposed fatal pathogenesis includes retrograde entry of the organism from the gastrointestinal tract via the pancreatic duct to the pancreas and subsequent peritonitis. This is the first reported fatality caused by this organism.

Can renal acute tubular necrosis be differentiated from autolysis at autopsy?

We investigate the morphological characteristics that may differentiate between ischemic acute tubular necrosis (ATN) and autolysis in postmortem samples. Renal tissue from 57 postmortem cases with an antemortem diagnosis of ATN and 57 age-/sex-matched control cases were examined for 10 morphological characteristics: epithelial proliferation (Ki-67 immunoperoxidase positivity), fibrin thrombi, tubular epithelial whorls, mitoses, casts, autolysis, tubulorrhexis, epithelial flattening, interstitial inflammation, and interstitial expansion. Tubular epithelial whorls were found in 16 ATN cases and were absent in controls. These findings suggest that specific morphological criteria may distinguish ischemic ATN from autolysis. Diagnoses of ATN may be confirmed using these combined criteria as contributing to cause of death and/or to ascertain previously undiagnosed cases of ATN postmortem.