Selective location of palisaded myofibroblastoma with amianthoid fibres.

Abstract

The occurrence of a palisaded myofibroblastoma with amianthoid fibres in the left inguinal lymph node of a 51 year old man prompted an investigation of the factors underlying its exclusive location. The antigen profile was characternsed which confirmed the homogeneous expression of vimentin and smooth muscle actin as well as the lack of desmin. Use of monoclonal antibodies to check for a differential distribution of myofibroblasts and the putative cell of origin of palisaded myofibroblastoma showed that inguinal lymph nodes have abundant vimentin and actin positive cells and desmin negative cells. This suggests that the selective occurrence of myofibroblastoma is related to the nodal microenvironment, providing a source of available and potentially proliferating myofibroblasts. Mast cells abounded in this lesion, particularly around amianthoid fibres, as well as in pelvic and inguinal lymph nodes.In view of the known role of mast cells in interstitial matrix degradation it is postulated that the core of amianthoid fibres represents degraded interstitial matrix, analogous to the sclerotic areas commonly found in the above mentioned lymph node groups, while the peripheral spokes, so peculiar to this entity, are the result of vimentin and smooth muscle actin, directly shed by -proliferating myofibroblasts.

Intranodal Palisaded Myofibroblastoma; a Case Report and Review of the Literature

“…Spindle cells of IPM were positive for SMA and vimentin but negative for S-100, Factor-VIII-related antigen, desmin, glial fibrillary acidic protein, epithelial membrane antigen and keratin antibodies [2,7]. Spindle cells were characterized by a continuous expression of actin and vimentin and lack of desmin in all reports in the literature [8]. Our case had also a Inflammatory cell component, lower cellularity similar immune profile.…”

“…Bigotti et al reported that actin positive/desmin negative myofibroblasts were diffusely prominent in inguinal lymph nodes compared with other lymph node regions. In addition, they suggested that the proliferation of myofibroblasts with this immunophenotype could be secondary to the increased drainage function in inguinal lymph nodes [8].…”

“…Submandibular and cervical lymph nodes were also reported as rare originating sites (4)(5)(6). To our knowledge, approximately 53 cases of IPM have been reported in the English-language literature (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). The ages of patients ranged from 19 years to 71 years.…”

Intranodal Palisaded Myofibroblastoma of Inguinal Region, a Rare Benign Lesion: Case Report

“…Schwannoma is quite uncommon in the inguinal region and it is positive for S 100 which differentiates it from IPM. Absence of Ebstein Barr Virus (EBV) DNA, negative immunostaining for HHV 8 and immunocompromised status favors the diagnosis of IPM rather than Kaposi's sarcoma.Also, there are no slit-like vascular channels, extravasated RBCs and no hyaline globules as seen in Kaposi's sarcoma [2][3][4][5][6][7][8][9] . Although the previous studies have provided comprehensive analysis of the characteristic clinicopathologic features of IPM, its pathogenesis remains unknown.…”

“…IPM was first described in English literature in 1968, although back then it was not classified as IPM. This current name was adopted because of its reflection of a myofibroblastic origin as well as prominent palisaded spindle cells histologically [1][2][3][4][5][6] . It is essential to differentiate IPM from other soft tissue tumors such as Schwannoma, Intranodal leiomyoma, Kaposi's sarcoma, inflammatory pseudotumor, solitary fibromastocytic tumor, angiomyomatous hamartoma and metastatic spindle cell lesions in the lymph node.…”