Gastroenterology Research, ISSN 1918-2805 print, 1918-2813 online, Open Access
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Case Report

Volume 19, Number 5, October 2026, pages 288-294

Localized Gastric Amyloid Light Chain Amyloidosis With Atypical Depressed Morphology: Diagnostic Implications Based on Magnifying Endoscopy

Figures

↓  Figure 1. A solitary 25-mm type 0-IIc lesion localized to the lesser curvature of the lower gastric body. (a) White-light endoscopy revealed an irregular, discolored depressed lesion. (b) Chromoendoscopy with indigo carmine demonstrated a coarse mucosal surface within the depressed area and an irregular “moth-eaten” appearance at the boundary between the lesion and the surrounding non-neoplastic mucosa.
Figure 1.
↓  Figure 2. Magnifying endoscopy with NBI. (a) A well-demarcated brownish area was observed. (b) Magnified view of the central part of the lesion showed obscured glandular structures with a mixture of normal-like architecture. Tortuous vessels were noted in areas with structural obscuration; however, no clearly atypical irregular microvascular patterns were identified. NBI: narrow-band imaging.
Figure 2.
↓  Figure 3. Magnifying endoscopy with NBI of the lesion margin. (a) A clearly demarcated depressed change was observed at the margin of the lesion. (b) Within the lesion, enlarged glandular structures and prominent vascular patterns were observed compared to the surrounding mucosa; however, no definite irregular glandular or vascular architecture suggestive of malignancy was identified. NBI: narrow-band imaging.
Figure 3.
↓  Figure 4. Endoscopic ultrasonography using a 20-MHz probe demonstrated homogeneous hypoechoic thickening confined to the second layer, with no evidence of deeper submucosal invasion.
Figure 4.
↓  Figure 5. Histopathological findings of biopsy specimens from the lesion. (a) No evidence of malignancy was observed, and amyloid deposition was identified mainly in the submucosa. (b) Congo red staining was positive for amyloid protein. (c) Immunohistochemical staining showed negativity for kappa light chain, (d) positivity for lambda light chain, (e) and negativity for amyloid A, (f) transthyretin, and (g) β2-microglobulin, confirming the diagnosis of AL (lambda-type) amyloidosis. AL: amyloid light chain.
Figure 5.

Table

↓  Table 1. Reported Cases of Localized Gastric AL Amyloidosis Presenting With Depressed Lesions
 
AuthorYearAgeSexSymptomLocationSize (mm)Endoscopic featureNBI findingsAmyloid typeUnderlying diseaseTreatment
Mucosal structureMicrovasculature
AL: amyloid light chain; ND: not described; SMT: submucosal tumor; NBI: narrow-band imaging; RA: rheumatoid arthritis; EMR: endoscopic mucosal resection; ESD: endoscopic submucosal dissection; APC: argon plasma coagulation; AL-λ: amyloid light-chain lambda-type; AL-κ: amyloid light-chain kappa-type.
1Yanai et al [6]199152FNoneLower gastric body25ErosionNDNDAL-λNDEMR
2Ebato et al [7]201277FAnemiaLower gastric body46DepressedNDNDALNDESD
3Yamaguchi et al [8]201549MNoneLower gastric body15SMT + depressedGroove-type surface pattern with an apparent demarcation lineNDALNDND
4Kagawa et al [9]201675MNoneLower gastric body15DepressedIrregular groove-type surface patternRound microvascular changesALNoneFollow-up
5Ahn et al [10]201855FNoneMid-gastric body20DepressedNDNDAL-κ/λBreast cancerFollow-up
6Furukawa et al [11]202056MNoneMid-gastric body40DepressedIrregular groove-type surface patternRound small changes and dilated vessels without caliberAL-κNDFollow-up
7Takahashi et al [12]202171FNoneLower gastric body25SMT + depressedNo microsurface irregularityDilated vessels without microvessel irregularityAL-λNoneESD
8Hashimoto et al [13]202149MNoneGastric antrum20SMT + depressedNDNDAL-λNoneFollow-up
9Iwamuro et al [14]202358MNDLower gastric body25DepressedNDNDAL-λNoneFollow-up
10Iwamuro et al [14]202359MNDLower gastric body20DepressedPartial absence of microstructural patternsEmphasized dilation of microvasculatureAL-λNoneFollow-up
11Iwamuro et al [14]202339MNDND15DepressedNDNDAL-κNoneAPC
12Iwamuro et al [14]202350MNDLower gastric body20DepressedPartial absence of microstructural patternsEmphasized dilation of microvasculatureAL-λNoneFollow-up
13Iwamuro et al [14]202351MNDND35DepressedNDNDAL-λNoneFollow-up
14Iwamuro et al [14]202362MNDUpper gastric body15DepressedNDNDAL-κNoneFollow-up
15Present case202678FNoneLower gastric body25DepressedPartially preserved glandular structuresTortuous vessels without definite irregularityAL-λRAFollow-up