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Case Reports
. 2025 Apr 14;17(4):e82228.
doi: 10.7759/cureus.82228. eCollection 2025 Apr.

Primary Localized Cutaneous Amyloidosis Presenting With Tumor-Like Swelling in the Lower Extremity: A Rare Presentation

Ahmed Almukhlifi  1 , Ayman Ibrahim  2 , Ahmed Hazazzi  3 , Noorah Almadani  4
Affiliations
Case Reports

Primary Localized Cutaneous Amyloidosis Presenting With Tumor-Like Swelling in the Lower Extremity: A Rare Presentation

Ahmed Almukhlifi et al. Cureus. .

Abstract

Amyloidosis consists of a spectrum of disease ranging from primary localized forms to secondary forms due to systemic disease. Amyloidoma, a variant of localized amyloidosis, is the least frequent manifestation of tissue amyloid deposition, which can be either amyloid A (AA) or amyloid light-chain (AL) type. Soft tissue amyloidoma is uncommon and mostly affects the abdomen and mediastinum and rarely affects the extremities. We present a middle-aged woman who developed a tumor-like swelling in the extremity, in which comprehensive investigations revealed features of primary amyloidosis with no evidence of internal involvement, representing a rare presentation.

Keywords: al kappa-type amyloidosis; amyloidoma; amyloidosis; extremity; nodular amyloidosis; primary localized cutaneous amyloidosis; soft tissue swelling; tumor.

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Conflict of interest statement

Human subjects: Consent for treatment and open access publication was obtained or waived by all participants in this study. Conflicts of interest: In compliance with the ICMJE uniform disclosure form, all authors declare the following: Payment/services info: All authors have declared that no financial support was received from any organization for the submitted work. Financial relationships: All authors have declared that they have no financial relationships at present or within the previous three years with any organizations that might have an interest in the submitted work. Other relationships: All authors have declared that there are no other relationships or activities that could appear to have influenced the submitted work.

Figures

Figure 1
Figure 1. Swelling of the left leg
Tumor-like swelling overlying the distal left tibia with smooth surface and no skin changes (arrowheads). (A) Medial view. (B) Lateral view.
Figure 2
Figure 2. MRI of the legs
There is a distal tibial well-demarcated soft tissue mass overlying the anteromedial tibia (arrowhead) associated with spiculated periosteal reaction (likely a superficial invasion). The mass contains a few internal calcification and demonstrates heterogeneous T1WI isointensity and heterogeneous T2 hyperintensity with heterogeneous postcontrast enhancement measuring 6.3 × 4.1 × 1.3 cm worrisome of underlying soft tissue sarcoma. T1WI: T1-weighted imaging; R: right; L: left
Figure 3
Figure 3. Histopathological features of amyloidosis
Histology (hematoxylin and eosin stain, 400×) reveals that homogeneous material is present as extracellular deposits and displays characteristic cracks. These densely eosinophilic material separated by connective tissue with chronic inflammation (A). Same section stained with Congo red (400×). The amyloid deposits have a bright orange-red appearance (B).
See this image and copyright information in PMC

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