Dados do Trabalho

Título

The Role of PET/CT in Detecting Occult Disease in Synchronous Tumors: A Case Report of Merkel Cell Carcinoma and Non-Hodgkin Lymphoma

Introdução/Justificativa

Merkel Cell Carcinoma (MCC) is a rare and aggressive cutaneous neoplasm characterized by a high tendency for recurrence and metastasis, primarily affecting older adults with fair skin. The introduction of PET/CT with 18F-FDG has significantly enhanced the diagnosis and management of MCC, providing superior sensitivity in detecting occult disease compared to computed tomography. This advancement profoundly impacts patient staging and therapeutic decisions. Similarly, non-Hodgkin lymphomas, a heterogeneous group of neoplasms originating from B cells, T cells, or natural killer cells, also benefit from PET/CT for diagnosis and follow-up, underscoring the significance of this modality in oncological practice. Herein, we present a rare case of synchronous Merkel cell carcinoma and non-Hodgkin lymphoma.

Relato

A 61-year-old male patient with a history of treated diffuse large B-cell lymphoma and multiple comorbidities presented with symptoms of progressive asthenia, night sweats without fever, weight loss, and a nodular reddish lesion on the left thigh; no palpable lymph nodes were found. Initial blood work showed pancytopenia; bone marrow biopsy did not reveal infiltration by high-grade histological non-Hodgkin lymphoma, but could not rule out focal infiltration by a low-grade histological lymphoma of immunophenotype B.

Further investigation included a skin nodule biopsy, histopathologically consistent with Merkel cell carcinoma. PET/CT revealed extensive neoplastic involvement, including a retroperitoneal mass, neoplastic involvement of multiple bilateral lymph node chains, diffuse hyperdensities throughout the body, and a pulmonary nodule. Biopsy of the retroperitoneal mass confirmed low-grade non-Hodgkin lymphoma, suggesting a follicular subtype.

The patient underwent resection of the Merkel cell carcinoma lesion in his thigh. A compromised deep margin was detected, warranting adjuvant radiotherapy and adjuvant chemotherapy with cisplatin + etoposide, administered concurrently with rituximab for lymphoma treatment.

Conclusão

This case underscores the complexity of diagnosing and treating synchronous neoplasms, emphasizing the need for a multidisciplinary and individualized approach. 18F-FDG-PET/CT plays a pivotal role in detecting occult disease and assessing the extent of the conditions in this setting.

Palavras Chave

PET/CT; Merkel Cell Carcinoma; Non-Hodgkin Lymphoma; Occult Disease