Background: Malignant melanoma (MM) generally presents as a primary neoplasm of the skin, and most MM cases of the respiratory system are metastatic. Primary MM of the lung (PMML) is quite rare, and its diagnosis is relatively difficult.Case presentation: We report the case of a 57-year-old male patient with PMML who denied any history of tumours. His initial complaint was frequent coughs with bloody sputum for 4 days. Chest radiography demonstrated a high-density shadow in the lower lobe of the right lung, which was suspected to be a large space-occupying lesion on subsequent computed tomography (CT) and to be a hypermetabolic tumour by positron emission tomography–CT. To confirm the diagnosis, exploratory surgery was performed. Finally, we confirmed the diagnosis of PMML.Conclusions: PMML is extremely rare and easily misdiagnosed as lung cancer. Because of its morphological and immunophenotypic variations, the diagnosis of PMML remains difficult. This case report discusses the diagnosis and case management of a patient while referring to the existing literature.

Background: N-cadherin is considered a characteristic protein of EMT and has been found to be closely related to tumor resistance. In this study, a novel molecular imaging probe, ^99mTc-HYNIC-ADH-1, was developed, and its diagnostic value in monitoring drug resistance in NSCLC was preliminarily investigated. Methods: ADH-1 was labeled indirectly with ^99mTc. Radiochemical purity and stability, partition coefficients and pharmacokinetics were evaluated. Additionally, the fluorescent probe of ADH-1 was synthesized to study tumor uptake in cells level and in vivo. Biodistribution analysis and small animal SPECT/CT were performed in PC9GR and PC9 tumor-bearing mice. Results: ^99mTc-HYNIC-ADH-1 was highly stable (radiochemical purity ≥ 98% in PBS and serum after 24 h). A cell binding study and fluorescence imaging showed that the uptake was significantly higher in PC9GR cells (gefitinib-resistant) than in PC9 cells (nonresistant) (p < 0.05). Biodistribution analysis showed rapid blood clearance and significant uptake in the kidney and resistant tumor. Small animal SPECT/CT studies showed that uptake in PC9GR tumors (T/NT = 7.73 ± 0.54) was significantly higher than that in PC9 tumors (T/NT = 3.66 ± 0.78) at 1 h (p = 0.002). Conclusions: The ^99mTc-HYNIC-ADH-1 molecular probe has a short synthesis time, high labeling rate, high radiochemical purity and good stability, does not require purification, is characterized by rapid blood clearance and is mainly excreted through the urinary system. ^99mTc-HYNIC-ADH-1 is considered a promising probe for monitoring drug resistance in NSCLC.

A 55-year-old man was diagnosed with gastric adenocarcinoma. ¹⁸F-FDG PET/CT was performed, which detected an enlarged nodule with increased uptake located in the omentum between the transverse colon and liver, thus lymph node metastasis was under suspicion. The patient subsequently underwent ⁶⁸Ga-FAPI PET/MRI clinical trial after signing the informed consent, which also revealed the abnormal focus with intense uptake. However, the histopathology of the nodule was unexpectedly diagnosed as fibrous hyperplasia after lymphadenectomy.