case_images: PMC11788013_01
case_images: Contrast computed tomography (CT) findings. Borderline well-defined mass lesion within the left thigh adductor muscle, with a 150-mm large fatty dense area (blue arrow) and a lightly contrasted solid area (red arrow) (a). Multiple areas of soft density with indistinct boundaries within the subcutaneous fat of the trunk (yellow arrow) (b). Hepatosplenomegaly (c). Fluorodeoxyglucose positron emission tomography-CT (PET-CT) showing an accumulation with a maximum standard uptake value (SUVmax) of 6.84 in the solid area of the mass (d).
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case_images: cnr270129-fig-0001
case_images: Contrast-enhanced computed tomography (CT) revealed a 150-mm large mass lesion with a mixture of fatty and 80-mm large solid areas within the left thigh adductor muscle (Figure 1a). Multiple masses showed soft tissue density with indistinct boundaries within the subcutaneous adipose tissue of the trunk and temple regions (Figure 1b). Other findings included bilateral cervical, axillary, mediastinal, abdominal, para-aortic to pelvic, and inguinal lymph node enlargement, as well as hepatosplenomegaly (Figure 1c). Fluorodeoxyglucose positron emission tomography-CT (PET-CT) showed an accumulation image with a maximum standard uptake value (SUVmax) of 6.84 in the solid area of the mass lesion within the left thigh adductor muscle (Figure 1d).
case_images: Specimen removed from the soft tissue tumor within the left thigh adductor muscle (a). Axial section cutout face of the tumor's superior side. Yellowish fatty areas (blue arrow) and grayish-white solid areas (red arrow) with relatively well-defined boundaries (b). A small amount of seemingly non-neoplastic fatty tissue (yellow arrow) around the fatty tumor (c). Microscopic image of the area marked as "d" in (b) (bordered by a white frame). Low-magnification image. A fibrous capsule formed between the fatty area with prominent mature adipocyte proliferation (lower part) and the grayish-white solid area with prominent lymphocyte proliferation (upper part) (d). Microscopic image of the area marked as "e" in (b) (bordered by a white frame). Medium-magnification image. Lymphocyte conglomerations scattered in islands around microvessels within the fatty area (e).
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case_images: cnr270129-fig-0002
case_images: The resected specimen showed a fatty tumor measuring 190 x 95 x 60 mm within the muscle and a grayish-white-toned solid area measuring 80 x 75 x 45 mm on the superior aspect of the mass (Figure 2a). The border between the fatty and solid areas was relatively clear; the fatty areas showed lobulated growth within the muscle tissue (Figure 2b). A small amount of gross non-neoplastic fatty tissue was observed around the specimens (Figure 2c). A fibrous capsule was noted at the border (Figure 2d). Scattered clusters of small lymphocytes were observed in the form of islands around small blood vessels within the adipose tumor area (Figure 2e).
case_images: Predominance of small lymphocytes, with some intervening plasma cells, in histological section of the specimen. Original magnification at image acquisition: x100 (a). Abundance of CD20-positive cells. Original magnification at image acquisition: x100 (b). Kappa staining showing a small number of positive cells. Original magnification at image acquisition: x100 (c). Lambda-positive cells were significantly more abundant than Kappa-positive cells. Original magnification at image acquisition: x100 (d). Fibrous septa were seen in the fatty areas, and hyperchromatic stromal cells were scattered. Original magnification at image acquisition: x200 (e). Hyperchromatic stromal cells were partially positive for CDK4. Original magnification at image acquisition: x200 (f). Small lymphocytes diffusely proliferated in the grayish-white solid area. Original magnification at image acquisition: x200 (g). A few CDK4-positive cells were intercalated within small lymphocytes. Original magnification at image acquisition: x200 (h). A few MDM2 signal-amplified cells (yellow arrow) were intercalated in lymphocytes, as determined via the FISH assay (i). Mature adipocytes in the fatty area showed amplification of MDM2 (yellow arrow), as determined via the fluorescence in situ hybridization assay (j).
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case_images: cnr270129-fig-0003
case_images: A predominance of CD20-positive cells and a high number of Lambda-positive cells compared with that of Kappa-positive cells was seen, suggesting lymphoma infiltration (Figure 3a-d). The adipose tumor area had relatively thick fibrous septa and scattered hyperchromatic stromal cells (Figure 3e). Immunohistochemistry revealed that the hyperchromatic stromal cells were positive for CDK4 (Figure 3f). The solid area at the superior aspect of the tumor was diffusely populated with small lymphocytes and was considered LPL because of similar histological findings and immunostaining results as those for the needle biopsy (Figure 3g). FISH revealed few intervening cells with amplified MDM2 signals (Figure 3h,i). FISH of mature adipocytes in the adipose tumor area confirmed MDM2 amplification, and this area was determined to be a WDL (Figure 3j).
case_images: Findings of hematoxylin and eosin (HE) staining at the border between fatty and solid areas (a). CD20-stained section of the specimen a. In the fatty tumor area (blue arrow), CD20-positive lymphoma islands are visible (b). Findings of HE staining at the border between fatty areas and non-neoplastic fatty tissue (c). CD20 staining of a section of the specimen (c). The fatty tumor area (blue arrow) shows foci of CD20-positive lymphoma cells, whereas the surrounding non-neoplastic fatty tissue (yellow arrow) shows no foci of CD20-positive lymphoma cells (d). Findings of HE staining of dissected inguinal lymph nodes and surrounding non-neoplastic fatty tissue (e). Nodular proliferation of CD20-positive cells within the lymph nodes, with no infiltration of CD20-positive cells in the surrounding fatty tissue (f).
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case_images: cnr270129-fig-0004
case_images: The lymphoma cell infiltrates were scattered in islands within the WDL area (Figure 4a,b). However, no lymphoma infiltration was observed in the non-neoplastic fatty tissue surrounding the tumor (Figure 4c,d). LPL cells as evident from light-chain restriction, which was confirmed via Kappa and Lambda staining. Lymphoma cells did not infiltrate the non-neoplastic fatty tissue surrounding the lymph nodes (Figure 4e,f).
case_images: Transcriptome analyses using RNA sequencing. Differentially expressed genes (DEGs) between non-neoplastic fat tissue and well-differentiated liposarcoma (WDL) with scant lymphoma cell infiltration are shown in the volcano plot (a). DEGs with |log2 fold change (FC)| >= 1 and p-value <= 0.05 are indicated with small red circles. Expression of genes with positive log2FC was upregulated in WDL. Expression of chemokine genes upregulated in WDL, demonstrated in terms of fragments per kilobase of exon per million reads mapped (FPKM) with log2FC and p-value (b). A heatmap of comparative gene expression among four examined tissues, shown at the bottom of the map. Gene symbols are provided on the right side of the map, with corresponding chemokine ligand genes within parentheses for receptor genes (c).
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case_images: cnr270129-fig-0005
case_images: This comparison revealed 13 754 differentially expressed genes (DEGs) with the absolute value of fragments per kilobase of exon per million reads mapped (FPKM) log2 fold change >= 1 and p-value <= 0.05 (Figure 5a). The DEGs included multiple chemokine genes showing significantly higher expression in WDL than in non-neoplastic fat tissue, including C-C motif ligand (CCL)5, CCL13, CCL18, CCL19, C-X-C motif ligand (CXCL)9, and CXCL10 (Figure 5a,b). A heatmap was prepared for comparative visualization of the chemokines and their corresponding receptors with enhanced gene expression (Figure 5c). Upregulated expression of CCR4 for CCL5, CCR6 for CCL18, and CCR7 for CCL19 was observed in lymph nodes, where lymphocytes were replaced by lymphoma cells (Figure 5c).