Cutaneous Apocrine Mixed Tumor With Intravascular Tumor Deposits: A Diagnostic Pitfall

Abstract

Apocrine mixed tumor of the skin is a benign adnexal neoplasm usually posing no diagnostic problem for a histopathologist. The purpose of our investigation is to present a small series of 4 benign cutaneous apocrine mixed tumors of the skin that contained small foci of intravascular tumor deposits, a feature not previously described, to the best of our knowledge. The 4 lesions were identified retrospectively after a review of 312 apocrine mixed tumors and 51 eccrine mixed tumors in the collective files of the authors. In all cases, this feature was originally overlooked. The patients were 3 men and 1 woman, ranging in age at diagnosis from 29 to 66 years. Locations included nose (2), forehead (1), and the fifth toe (1). Histopathologically, all 4 neoplasms demonstrated typical features of a benign apocrine mixed tumor; 2 cases were classified as hyaline cell-rich tumors. In all cases, there were either blood or lymphatic vessels containing small intraluminal collections of neoplastic cells, which had the appearances of hyaline cells and immunohistochemically expressed cytokeratins and were partly immunoreactive for S-100 protein and calponin, thus indicating the myoepithelial phenotype. The intravascular location of the neoplastic cells was confirmed by CD31 staining. The nature of the vessels (lymphatics vs. blood vessels) was supported by staining for alpha smooth muscle actin, which stained pericytes in blood vessels. Lymphatic vessels were also stained for D2-40. No eccrine mixed tumor manifested intravascular tumor deposits. Follow-up of the patients revealed no recurrences or metastasis (range: 2-21 years). It is concluded that occurrence of intravascular involvement in benign apocrine mixed tumor of the skin is rare (approximately 1%-2%). This feature is discrete and is easy to overlook. At present, its significance is not completely clear. Until proved otherwise in future, we suggest to consider intravascular deposits in cutaneous apocrine mixed tumors as an innocuous phenomenon.

Clinical and pathological study on mixed tumors of the skin

“…[ 23 ] There are rare cases of MTS invading small blood vessels, but there is no recurrence or metastasis during follow-up for many years. [ 24 ] The cases of the present study agreed with these histological features.…”

Hyaline Cell-Rich Apocrine Mixed Tumor with Cytologic Atypia

“…Hyaline cell-rich apocrine mixed tumor affects patients between their twenties and seventies with prominent male predilection [ 2 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. Earlier cases were located in extremities [ 2 , 4 , 5 ], whereas the recent cases also involved the face and neck [ 6 , 8 , 9 ], in addition to extremities [ 7 , 8 , 9 , 10 ]. The sizes of the tumor were approximately up to 25 mm [ 2 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ].…”

“…Earlier cases were located in extremities [ 2 , 4 , 5 ], whereas the recent cases also involved the face and neck [ 6 , 8 , 9 ], in addition to extremities [ 7 , 8 , 9 , 10 ]. The sizes of the tumor were approximately up to 25 mm [ 2 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ].…”

“…In 1989, Argenyi et al [ 3 ] reported that hyaline cells were relatively common in apocrine mixed tumor, and that they frequently showed signs of degeneration, ranging from ballooning to fragmentation. Kazakov et al [ 9 ] reported 4 cutaneous apocrine mixed tumors with intravascular tumor deposits. In all cases, there were either blood or lymphatic vessels containing small intraluminal neoplastic cells, which had the appearance of hyaline cells.…”

“…Despite being a relatively common cell type, the hyaline cell-rich variant is rare. Approximately 30 cases of hyaline cell-rich apocrine mixed tumor, also known as hyaline cell-rich chondroid syringoma, have been reported to date [ 2 , 4 , 5 , 6 , 7 , 8 , 9 , 10 ]. A previous study reported that 17 out of 18 apocrine mixed tumors with cytologic atypia were a hyaline cell-rich variant [ 8 ].…”