Faculty Bibliography

We studied the suitability of commercially available monoclonal antibodies (mAbs) for the immunohistochemical (IHC) detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) in standard archival specimens. Antibodies were screened on HEK293 cells transfected with viral nucleoprotein, S1 subunit and S2 subunit of spike protein and on untransfected cells, as well as a panel of normal tissue. Lung tissue with presence of SARS-CoV2 confirmed by in situ hybridization (ISH) was also used. A total of 7 mAbs were tested: (1) mAb 001 (Sino Biological, 40143-R001), (2) mAb 007 (Sino Biological, 40150-R007), (3) mAb 019 (Sino Biological, 40143-R019), (4) mAb 1A9 (GeneTex, GTX632604), (5) mAb ABM19C9 (Abeomics, 10-10007), (6) FIPV3-70 (Santa Cruz, SC-65653), and (7) mAb 6F10 (BioVision, A2060). Only 2 mAbs, clone 001 to the nucleoprotein and clone 1A9 to the S2 subunit spike protein displayed specific immunoreactivity. Both clones showed strong staining in the acute phase of COVID-19 pneumonia, mostly in areas of acute diffuse alveolar damage, but were not completely congruent. Viral protein was also found in kidney tubules, endothelia of multiple organs and a nasal swab of a patient with persistent SARS-CoV2 infection. The other tested reagents were either poorly reactive or demonstrated nonspecific staining in tissues and lesions not infected by SARS-CoV2. Our study demonstrates that rigid specificity testing is mandatory for the evaluation of mAbs to SARS-CoV2 and that clones 001 to nucleoprotein and 1A9 to S2 subunit spike protein are useful for the in situ detection of SARS-CoV2.

INTRODUCTION/BACKGROUND:We describe postmortem pulmonary histopathologic findings of COVID-19 pneumonia in patients with a spectrum of disease course, from rapid demise to prolonged hospitalization. METHODS:Histopathologic findings in postmortem lung tissue from eight patients who died from COVID-19 pneumonia were reviewed. Immunohistochemistry (IHC) and next generation sequencing (NGS) were performed to detect virus. RESULTS:Diffuse alveolar damage (DAD) was seen in all cases with a spectrum of acute phase and/or organizing phase. IHC with monoclonal antibodies against SARS-CoV-2 viral nucleoprotein and spike protein detected virus in areas of acute but not organizing DAD, with intracellular viral antigen and RNA expression seen predominantly in patients with duration of illness less than 10 days. Major vascular findings included thrombi in medium and large caliber vessels, platelet microthrombi detected by CD61 IHC, and fibrin microthrombi. CONCLUSIONS:Presence of SARS-CoV-2 viral RNA by NGS early in the disease course and expression of viral antigen by IHC exclusively in the acute but not in the organizing phase of DAD, suggests that the virus may play a major role in initiating the acute lung injury of DAD, but when DAD progresses to the organizing phase, the virus may have been cleared from the lung by the patient's immune response. These findings suggest the possibility of a major change during the disease course of COVID-19 pneumonia that may have therapeutic implications. Frequent thrombi and microthrombi may also present potential targets for therapeutic intervention.

Excision repair cross-complementation group 1 (ERCC1) expression by non-small cell lung cancer (NSCLC) has been reported to predict resistance to platinum-based therapies. On this basis, several commercial laboratories have offered ERCC1 testing to facilitate clinical decision making, but the reliability of such assays has recently been called into question. Methods. First, three large commercial laboratories were queried for their cumulative ERCC1 test results in NSCLC patients to compare their independent rates of ERCC1 expression. Second, identical tumor blocks from individual NSCLC patients underwent round-robin analysis to evaluate interlaboratory concordance for ERCC1 expression. Third, a retrospective review of medical records from NSCLC patients identified those who were both highly responsive and resistant to platinum-based chemotherapies. Tumor blocks from these patients were then used in a gold standard analysis to determine individual laboratory sensitivity and specificity for ERCC1 results. Results. Significant differences were observed in independent laboratory ERRC1 expression rates (Clarient 70% vs. Genzyme 60% vs. Third Laboratory 44%, p < .0001 for all two-way comparisons). Only 4 of 18 tumors examined in round-robin analysis were fully concordant (κ ≤ 0.222 for all two-way comparisons). In preselected platinum responsive and resistant specimens, none of these three commercially marketed laboratory assays achieved a specificity of greater than 50%. Conclusion. The results of commercial laboratory testing for ERCC1 are inconsistent and unreliable. Better validation and postmarketing surveillance should be mandated before tumor biomarker assays are allowed to enter the clinical arena.

Cutaneous presentations of bronchogenic cysts are rare in all age groups. Previous reports of cutaneous manifestations of bronchogenic cysts have been described as nodular, adherent masses, most frequently with a suprasternal location. We report a unique presentation of an infant with a pedunculated, anterior chest wall mass, which was identified as a bronchogenic cyst.

The objective of this study is to discuss the presentation, diagnosis, and surgical management of a young, healthy patient with a symptomatic mesenteric cyst. He had a 5-month history of abdominal pain from this disorder, and the case is presented to illustrate the clinical picture and operative management of this rare disorder.

Sarcomatoid change has been well documented in the various subtypes of renal cell carcinoma (RCC) and its presence is known to portend a worse prognosis in RCC. Mucinous tubular and spindle cell carcinoma is a RCC subtype, which is defined as polymorphous histology wherein the spindled epithelial cell is an inherent carcinomatous component. Many of these putatively low-grade tumors have been previously misdiagnosed as unclassified or sarcomatoid papillary RCC. We present 2 examples of hitherto undescribed sarcomatoid change in mucinous tubular and spindle cell carcinoma in a 71-year-old woman and an 80-year-old man who both underwent a radical nephrectomy procedure. In addition to the classic mucinous tubular and spindle cell carcinoma morphology, both cases had a sarcomatoid component characterized by predominantly high-grade spindle cells, solid pleomorphic epithelioid cells, and malignant fibrous histiocytoma-like storiform patterns. Sarcomatoid change comprised 60% and 20% of the tumors, respectively. Unlike the spindle sarcomatoid cells, the inherent spindle cell elements of mucinous tubular and spindle cell carcinoma had distinctively low-grade cytology and occasionally blended with tubular structures and variable mucinous stroma. The sarcomatoid cells were associated with significant necrosis, marked nuclear pleomorphism, mitoses of up to 5/10 high power field, higher proliferation fraction (MIB1), and loss of alpha-methylacyl-CoA racemase or cytokeratin 7 expression. Cytogenetic analysis in 1 tumor showed loss of chromosomes 14 and 15 and gains of chromosomes 2, 5, 7, 9, 10, 12, 17, 19, 20, 22, and X. Widespread metastasis to lymph nodes, bones and lungs occurred in one patient who succumbed 9 months after nephrectomy. Helpful features in distinguishing spindle cells of sarcomatoid component versus that of the native tumor include the presence of high-grade cytology, expansile growth with loss of typical imperceptible blending with the tubulo-papillary component, extensive necrosis, high mitotic activity, high proliferation fraction, and loss of expression of alpha-methylacyl-CoA racemase that contrasted the classic areas. Distinction of the sarcomatoid histology from inherent spindle cell component of mucinous tubular and spindle cell carcinoma is important because of its unfavorable prognostic implication.

Fever of unknown origin (FUO) characterizes febrile disorders that are accompanied by prolonged fevers of 101 degrees F or greater for 3 weeks or more that remain undiagnosed after comprehensive inpatient and outpatient diagnostic testing. At the present time, malignancies are the most common cause of FUOs. Among malignant FUOs, lymphomas are the most common. We present the case of a non-Asian young adult man who presented with FUO. He had no peripheral adenopathy or splenomegaly but was found to have anterior/superior mediastinal adenopathy and right paratracheal adenopathy. His diagnostic workup was negative for rheumatic/inflammatory and infectious diseases. Laboratory test results were unremarkable except for a highly elevated erythrocyte sedimentation rate and highly elevated serum ferritin level. Otherwise unexplained highly elevated serum ferritin levels in patients with FUOs suggest rheumatic and inflammatory disorders, for example, systemic lupus erythematosus flare or malignancy. The findings of mediastinal adenopathy combined with a highly elevated ESR and highly elevated serum ferritin levels indicate lymphoma as the most likely diagnosis. He also had polyclonal gammopathy on serum protein electrophoresis (SPEP). In a patient with FUO, negative blood cultures, and a heart murmur, polyclonal gammopathy on SPEP suggests atrial myxoma. Lymphomas are often associated with elevated alpha(1)/alpha(2) globulins on SPEP. Lymph node biopsy of the mediastinal nodes was negative for lymphoma but did not show characteristic emperiopolesis, pathognomonic of Rosai-Dorfman disease, a benign lymphoproliferative disorder. Rosai-Dorfman disease usually presents with massive bilateral cervical adenopathy but may present with lymph node involvement in other sites, as in this case. In patients with lymphadenopathy and a negative FUO workup, clinicians should consider the possibility of Rosai-Dorfman disease, particularly if accompanied by an otherwise unexplained highly elevated serum ferritin levels and polyclonal gammopathy on SPEP.

Severe acute respiratory syndrome (SARS) is an infectious condition caused by the SARS-associated coronavirus (SARS-CoV), a new member in the family Coronaviridae. To evaluate the lung pathology in this life-threatening respiratory illness, we studied postmortem lung sections from 8 patients who died from SARS during the spring 2003 Singapore outbreak. The predominant pattern of lung injury in all 8 cases was diffuse alveolar damage. The histology varied according to the duration of illness. Cases of 10 or fewer days' duration demonstrated acute-phase diffuse alveolar damage (DAD), airspace edema, and bronchiolar fibrin. Cases of more than 10 days' duration exhibited organizing-phase DAD, type II pneumocyte hyperplasia, squamous metaplasia, multinucleated giant cells, and acute bronchopneumonia. In acute-phase DAD, pancytokeratin staining was positive in hyaline membranes along alveolar walls and highlighted the absence of pneumocytes. Multinucleated cells were shown to be both type II pneumocytes and macrophages by pancytokeratin, thyroid transcription factor-1, and CD68 staining. SARS-CoV RNA was identified by reverse transcriptase-polymerase chain reaction in 7 of 8 cases in fresh autopsy tissue and in 8 of 8 cases in formalin-fixed, paraffin-embedded lung tissue, including the 1 negative case in fresh tissue. Understanding the pathology of DAD in SARS patients may provide the basis for therapeutic strategies. Further studies of the pathogenesis of SARS may reveal new insight into the mechanisms of DAD.