[Update on collaborative autopsy-based research in German pathology, neuropathology, and forensic medicine]

BACKGROUND

Autopsies are a valuable tool for understanding disease, including COVID-19.

MATERIALS AND METHODS

The German Registry of COVID-19 Autopsies (DeRegCOVID), established in April 2020, serves as the electronic backbone of the National Autopsy Network (NATON), launched in early 2022 following DEFEAT PANDEMIcs.

RESULTS

The NATON consortium's interconnected, collaborative autopsy research is enabled by an unprecedented collaboration of 138 individuals at more than 35 German university and non-university autopsy centers through which pathology, neuropathology, and forensic medicine autopsy data including data on biomaterials are collected in DeRegCOVID and tissue-based research and methods development are conducted. More than 145 publications have now emerged from participating autopsy centers, highlighting various basic science and clinical aspects of COVID-19, such as thromboembolic events, organ tropism, SARS-CoV‑2 detection methods, and infectivity of SARS-CoV-2 at autopsy.

CONCLUSIONS

Participating centers have demonstrated the high value of autopsy and autopsy-derived data and biomaterials to modern medicine. The planned long-term continuation and further development of the registry and network, as well as the open and participatory design, will allow the involvement of all interested partners.

[Uncommon tumor of the gastric wall]

We report on a 72-year-old male patient suffering from weight loss, diarrhea, and epigastric pain. By means of endosonographic ultrasound, a well-circumscribed tumor mass was found in the gastric wall, suggesting a gastrointestinal stromal tumor (GIST). Biopsies were taken and processed for standard histopathological analysis. The microscopy revealed uniform, small, round cells with central nuclei and prominent cell borders embedded in vascularized stroma. Immunohistochemistry demonstrated the expression of actin, but showed negativity for cytokeratin, CD34, CD117, DOG‑1, desmin, and CD45. The tumor was diagnosed as a gastral glomus tumor. The diagnosis was confirmed in the wedge resection specimen. Gastral glomus tumors are rare intramural tumors of the stomach. GIST and neuroendocrine tumor (NET) present the main differential diagnoses. Especially with regard to the epithelioid variant of GIST, clear separation can be difficult. Besides standard histological examination, immunohistochemistry and molecular analysis can be helpful since gastral glomus tumors do not obtain c‑Kit- or PDGFRα mutations. Based on the fact that this tumor most commonly shows a benign biological behavior, the prognosis of gastral glomus tumors is favorable.

[Bronchoalveolar lavage in hairy cell leukemia with pulmonary infiltration]

We report a 78-year-old male patient suffering from hairy cell leukemia, presenting clinically mainly with dyspnea. Radiology exhibited bilateral ground-glass shadows. In order to prevent pneumonia as a possible side effect due to conventional chemotherapy, it was decided to first treat the patient with rituximab; however, dyspnea persisted. Therefore, bronchoscopy was performed and specimens were sampled for both histological examination and bronchoalveolar lavage (BAL) analysis. BAL showed lymphocytosis (28.7%), and by means of immunocytochemistry a few CD79a+ B‑lymphocytes as well as lymphoid cells positive for the hairy cell marker DBA44 were observed. In addition, molecular study revealed the BRAF V600E mutation. Thus, the findings of BAL were interpreted as lung infiltration by hairy cell leukemia. This result was confirmed by histology. Following a therapy switch to cladribine, a significant improvement was reached. Pulmonary infiltrates by hairy cell leukemia were rarely described. This case represents the first report of hairy cell leukemia diagnosed by means of BAL. It may be difficult to clearly separate between lymphoma infiltration of the lung and medicamentous pneumonitis, but this differential diagnosis can be supported by morphological methods.

[Sarcoma of the spleen with MDM2 expression]

Primary sarcomas and sarcoma metastases are a rarity in the spleen. We report on the case of a 69-year-old male patient presenting with unclear abdominal symptoms and computed tomography (CT) revealed a tumor mass in the spleen. Histologically the tumor mass predominantly showed features of a spindle cell sarcoma with lymphoid infiltrates. The expression and amplification of MDM2 could be demonstrated by means of immunohistochemistry and fluorescence in situ hybridization (FISH). Furthermore, staging examinations did not reveal indications of any other primary tumors. These preliminary findings were suggestive of a dedifferentiated liposarcoma; however, in the further diagnostic work-up the tumor showed strong expression of CD21 and CD23 and was ultimately diagnosed as a follicular dendritic cell sarcoma (FDCS). The case emphasizes that MDM2 expression represents a possible pitfall in the diagnosis of spindle cell tumors. The differential diagnostic distinction between FDCS and a dedifferentiated liposarcoma is discussed.