Collision tumor of pulmonary adenocarcinoma and small lymphocytic lymphoma: A rare case of concurrent malignancies in the same lymph node.

BACKGROUND

Collision tumors, a rare and challenging diagnostic entity, are characterized by the simultaneous presence of two distinct histological neoplasms within the same anatomical site. The underlying mechanisms of collision tumors are not well understood, though various theories attempt to explain this phenomenon.

CASE PRESENTATION: A 77-year-old Palestinian man, a heavy smoker with multiple comorbidities, presented with a productive cough and significant weight loss. Computed tomography (CT) scan with IV contrast revealed extensive pulmonary involvement, mediastinal lymphadenopathy, and adrenal gland nodules. An excisional biopsy of a lymph node confirmed the presence of both metastatic pulmonary adenocarcinoma and small Lymphocytic Lymphoma (SLL) through histopathological and immunohistochemical analyses.

DISCUSSION: Collision tumors have been documented in various anatomical sites, such as the lung, gastrointestinal tract, skin, and genitourinary system. However, their occurrence in lymph nodes is exceptionally rare. Additionally, to our knowledge, a collision tumor involving both pulmonary adenocarcinoma and small lymphocytic lymphoma within the same lymph node has not been previously reported.

CONCLUSION

Collision tumors are uncommon and should be considered in the differential diagnosis of complex oncological cases. Accurate diagnosis requires comprehensive investigations, including imaging studies and detailed pathological examinations.