A 49-year-old male underwent ¹⁸F-FDG PET/CT after having diagnosed as anaplastic lymphoma kinase (ALK) negative anaplastic large cell lymphoma (ALCL) following a biopsy from a lesion located at left inguinal area.

Hypermetabolism at lymph nodes, liver, spleen, vertebral colon, and pelvic bones is compatible with multiple metastases.

ALCL is a rare type of non-Hodgkin lymphoma (NHL). It is divided into two entities according to the expression of ALK. It is an FDG avid malignancy and ALK expression is related to higher FDG uptake. ALK-positive patients tend to have better progression free survival than ALK-negative patients.

A 72-year-old male underwent ¹⁸F-FDG PET/CT for pretreatment staging after having diagnosed as NHL with small lymphocytic lymphoma subtype.

Splenomegaly together with increased FDG uptake is consistent with metastatic involvement of spleen. Although FDG uptake is not intense, hypermetabolism at lymph nodes is also suggestive of metastasis.

¹⁸F-FDG PET/CT is an effective method in the evaluation of metastatically involved lymph nodes which are reported as normal on CT depending on the size criterion. It is also superior to CT in the evaluation of diffusely infiltrated sites, such as the spleen or bone marrow. Sensitivity and specificity of PET/CT were higher than those of the other diagnostic modalities alone when the initial staging of splenic lymphomatous involvement is concerned.

A 72-year-old male, status post left axillary lymph node excisional biopsy proven to be Diffuse Large B-Cell Lymphoma (DLBCL) underwent ¹⁸F-FDG PET/CT for pretreatment staging.

Increased FDG uptake sites at infra- and supraabdominal lymph node stations, liver, spleen, and bony structures are compatible with metastatic involvement of lymphoma. Diffuse increased bone marrow uptake at proximal humeri and both femurs is due to hematopoietic activation.

FDG uptake pattern in spleen is heterogenous and multifocal in metastatic infiltration, whereas diffuse and mild in bone marrow activation.

A 49-year-old male, status post left orchiectomy proven to be DLBCL, underwent ¹⁸F-FDG PET/CT scan for pretreatment staging.

Hypermetabolic retroperitoneal lymph node masses at left iliac lymphatic chain is compatible with metastatic involvement of lymphoma. The lesions showed complete remission after chemoradiotherapy.

Primary testicular lymphoma (PTL) comprises around 1–2 % of all NHL. It primarily affects men, with a median age of 67 years. The most common histological subtype is DLBCL, accounting for 80–90 % of PTLs. ¹⁸F-FDG PET/CT is currently the standard procedure for assessment of the posttreatment response for most lymphoma subtypes.

A 72-year-old male, status post duodenum biopsy proven to be DLBCL, underwent ¹⁸F-FDG PET/CT for pretreatment staging.

Hypermetabolism involving the duodenum compatible with extranodal lymphoma.

Although the GI tract is the predominant site of extranodal lymphomas (ENL), primary lymphomas of the GI tract are rare. 50–60 % of all primary GI lymphomas are NHL. Many of these tumors are of the B-cell type. The duodenum is the most infrequent site of these lesions. ¹⁸F-FDG PET-CT has a significant advantage for the diagnosis of diffusely infiltrating organ involvements and is superior to contrast enhanced CT.

A 39-year-old male underwent ¹⁸F-FDG PET/CT after having diagnosed as gastric NHL following a biopsy from stomach. PET/CT study was repeated 4.5 months after the patient received chemotherapy and radiotherapy.

Diffuse and intensely increased FDG uptake at gastric wall represents primary malignant disease and hypermetabolic intraabdominal and supraclavicular (Virchow’s node) lymph nodes reflect involvement with primary malignancy. Resolution of all lesions at second study indicates complete remission as a result of chemoradiotherapy.