Solitary Amyloidoma of Soft Tissue: A Report of an Unusual Presentation with Review of Literature

Thomas Busch; Aziz Mohamad

doi:https://doi.org/10.47739/2373-9819/1149

Solitary Amyloidoma of Soft Tissue: A Report of an Unusual Presentation with Review of Literature

Case Report | Open Access | Volume 6 | Issue 2

Article DOI : https://doi.org/10.47739/2373-9819/1149

Thomas Busch^1* Aziz Mohamad¹

^1. Department of Pathology, American University of the Caribbean, USA

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Corresponding Authors

Thomas Busch, Department of Pathology, American University of the Caribbean, 11530 Upland Way, Cupertino CA, USA, Tel: (408) 893 - 9407

Abstract

Amyloidoma is a rare presentation of tissue amyloid deposition usually seen in the respiratory, genitourinary, and gastrointestinal tracts, but has also been reported in the mediastinum, central nervous system, skin, breast, and soft tissue. In this case, a 55-year-old man presented with a 5-cm soft tissue mass in the gluteal region, suggestive of a lipoma. Eventually the mass was found to be an isolated amyloidoma associated with a localized plasmacytoma. Soft-tissue amyloidoma in the absence of systemic amyloidosis or plasma cell dyscrasia in bone marrow is uncommon, and those localized to the extremities are extremely rare.

Keywords

Amyloidoma; Primary amyloidosis; Plasmacytoma; Soft-tissue; Extremity

Citation

Busch T, Mohamad A (2018) Solitary Amyloidoma of Soft Tissue: A Report of an Unusual Presentation with Review of Literature. JSM Clin Case Rep 6(2): 1149.

ABBREVIATIONS

AL: Aamyloid Light; SEP: Solitary Extramedullary Plasmacytoma; MM: Multiple Myeloma; FLC: Immunoglobulin Free Light Chain

INTRODUCTION

Amyloidoma is a rare presentation of tissue amyloid deposition in the absence of systemic amyloidosis. Insoluble amyloid fibrils form through spontaneous oligomerization of soluble protein precursors into a cross β-pleated sheet quaternary structure; the type of precursor protein and tissue distribution determine the clinical manifestations. The mechanism of amyloidogensis is the subject of intense study for its implication of direct cytotoxicity in a myriad of human diseases accounting for significant morbidity and mortality. In vitro studies reveal a characteristic flexible molecular configuration with high surface area-tohydrophobicity index conferring propensity for binding lipid membranes [1]. We here report a case of soft-tissue amyloidoma in the lower extremity.

CASE PRESENTATION

A 55-year-old man presented with a solitary nodular soft tissue mass palpable over the gluteal muscles, suggestive of a lipoma. The mass was surgically excised and the gross specimen measured 5.0 x 3.0 x 2.0 cm with a central area of softening. The original excision showed lesion cells at the surgical margin, so it was followed by re-excision with adequate safe margins. Histologically, the mass showed prominent sheet-like deposits of proteinaceous material (Figure 1A).

Figure 1 Amyloidoma in a Background of Plasmacytoma.

A. Light micrograph of excised mass demonstrating solid sheets of extracellular proteinaceous hyaline deposits, hematoxylin-eosin staining, original magnification x5

B. An inflammatory infiltrate is visible which includes syncytial cells (arrow), hematoxylin-eosin staining, and original magnification x20

C. The deposits take up Congo-Red stain with a brightly-colored appearance when analyzed under cross polarized light, original magnificationx40

D. Degenerating cell aggregates positive for surface CD-138, x40 original magnification

E. The deposits exhibit strong κ positivity, original magnification x40

F. The deposits exhibit weak λ positivity, 80X original magnificationx40

Lymphoplasmacytoid cells and multinucleated giant cells were present (Figure 1B). The proteinaceous material took up Congo-Red stain, which appeared brightly colored against a dark background when analyzed under cross-polarized light, indicative of amyloid (Figure 1C). Degenerated cellular aggregates are visible surrounding the amyloid, which stained positive for CD138 and monoclonal κ light chain and negative for Leukocyte Common Antigen (LCA), CD20, and λ light chain (Figure 1D,E,F). Serum protein electrophoresis was positive for monoclonal κlight chain. Bone marrow immunohistochemistry for clonal plasma cells was unremarkable. The mass was diagnosed as amyloidoma associated with localized solitary extramedullary plasmacytoma (SEP).

DISCUSSION

The case presented here highlights the importance of differentiating whether soft-tissue amyloidoma of the extremity represents primary or secondary amyloid and whether it was produced locally or systemically. An accurate diagnosis of SEP can guide deferral of systemic chemotherapy until definitive evidence of disseminated disease is discovered, thus minimizing patient harm.

The most common cause of amyloidoma is systemic amyloidosis associated with malignancy, chronic inflammation, genetic factors, and iatrogenic insults. In developed countries, Primary Amyloidosis (AL) is the most common type of systemic amyloidosis, is associated with plasma cell neoplasm, and has a median survival of just over three years [2]. Amyloid is demonstrated on microscopy by Congo-Red positivity and colored birefringence when analyzed under cross-polarized light. Immunoglobulin free light chains (FLC) are the precursors to AL amyloid fibrils; total body burden of monoclonal FLC from plasma cell dyscrasia correlates with spectrum of organ involvement and survival [3]. Complete workup for AL amyloidosis in warranted in all cases of biopsy-documented amyloidoma without family history of amyloidosis, infectious or chronic inflammatory conditions, or end-stage renal disease. The differential diagnosis includes solitary extra medullary plasmacytoma (SEP), solitary plasmacytoma of bone, or multiple myeloma (MM), which are cytologically equivalent but variable in prognosis. Surgical exploration with complete excision can be curative for SEP, but the standard treatment modality when there is bone involvement, high-dose anti-plasma cell chemotherapy with adjunctive autologous stem-cell transplantation, is associated with significant early mortality [2-4]. SEPs account for approximately 3 percent of plasma cell malignancies [5]. It is important to note the tendency of SEP to recur or evolve into disseminated disease if incompletely resected, which illustrates the importance of accurate diagnosis, prompt treatment, and close follow-up for optimizing patient outcomes [6-7].

To our knowledge, thirty-six cases of soft-tissue amyloidoma localized to the extremities have been previously described in the English language (Table 1).

Table 1: Reports of soft-tissue amyloidoma in the extremities, listed chronologically

Table 1: Reports of soft-tissue amyloidoma in the extremities, listed chronologically
Case	Authors	Age/Sex	Mass location	Amyloid type	Medical history
1	Lipper and Kahn [22]	57/F	Groin	NS	NS
2	Wilson and Rich [23]	72/F	Thigh	NS	Breast carcinoma
3	Reese et al.[10].	50/M	Popliteal fossa bilaterally	B2-microglobulin	CRF with dialysis. CTS
4	Floege et al.[12].	62/M	Gluteal region	B2-microglobulin	Dialysis. tuberculosis. CTS. THA. tenosynovitis
5	Sethi et al.[11].	48/M	Gluteal region	B2-microglobulin	Dialysis. polyarthropathy. CTS. macroglossia
6	Tom et al.[8].	47/F	Gluteal region bilaterally	B2-microglobulin	Dialysis. femoral neck fracture
7	Comensa et al.[14].	49/F	Multifocal shoulder. hip. hand	NS. probable AL	Multiple Myeloma
8	Vadmal et al.[24].	72/F	Distal leg	AA	Primary biliary cirrhosis. non-Hodgkin lymphoma
9	Sidoni et al.[25].	61/F	Multifocal leg	AA	Various autoimmune disorders
10	Flores et al.[15].	36/F	Popliteal fossa	AL	Mental retardation
11	Romagnoli et al. [26].	66/F	Leg	AA	Diabetes. HTN
12	Aoki et al.[9].	40/M	Popliteal fossa bilaterally	AA	Dialysis. CTS. femoral head lesion
13	Khoo [16]	40/M	Hip	AL	None
14	Sahoo et al.[27].	54/M	Shoulder	NS	Diabetes
15	Mukhopadhyay et al.[17].	45/M	Ankle	AL	Diabetes. multiple surgeries for traumatic ankle fractures complicated by infection
16	Sheldon and Forrester [28]	70/F	Popliteal fossa	NS	Dialysis
17	Bardin et al.[29].	77/M	Proximal arm	AA	Diabetes. HTN. prolonged smoking. peripheral neuropathy. nephrolithiasis. PAD
18	Iguchi et al.[18].	59/M	Gluteal region	AL	Lymphoplasticdyscrasia
19	Joung et al.[19].	61/M	Multifocal inguinal region bilaterally	AL	Multiple Myeloma
20	Pasternak et al.[30].	85/F	Leg	AL	Hyperlipidemia. gastritis. diverticulosis. hypothyroidism
21	Maheshwari [31]	NS/NS	Thigh	NS	NS
22-30	Walsh et al.[20].	NS/NS	Upper and lower extremities	AL	Extra-nodal lymphoma
31	Montagna et al. [32].	NS/NS	Gluteal region bilaterally	NS	Dialysis
32	Beggs et al.[33].	69/M	Thigh	NS	COPD. HTN. knee osteoarthritis
33	Elkins et al.[34].	NS/M	Multifocal calf	NS	NS
34	Clark et al.[35].	75/F	multifocal lower extremities bilaterally	NS	NS
35	Billaro et al.[36].	65/F	Ankle	AA	Sarcoidosis
Abbreviations: NS: Not Specified. AL: Amyloid Light. AA: Amyloid Associated. CRF: Chronic Renal Failure. CTS: Carpel Tunnel Syndrome. THA: Total Hip Arthroplasty. HTN: Hypertension. PAD: Peripheral Artery Disease. COPD: Chronic Obstructive Pulmonary Disease

Four identified B2-microglobulin amyloid associated with chronic hemodialysis [8-12]. One identified insulin-derived amyloid (Amylin) at an injection site in a long-standing diabetic [13]. Seventeen cases were confirmed AL amyloidoma; of these, two were associated with MM and eight were associated with extra-nodal lymphoma [14- 20]. Novel radioisotopes and monoclonal antibodies targeting amyloidogenic precursors and mature amyloid fibrils forecast a bright horizon of diagnostic and therapeutic advancement [1,2,21]. At present, however, clinicians need to rely on careful history-taking and biopsy for rapid assessment of potentially dangerous B-cell-derived clones to facilitate appropriate diagnosis and initiate individualized treatment.