Malignant mixed tumor of the skin (malignant chondroid syringoma)

Malignant Chondroid Syringoma: A Report of Two Cases with a Sarcomatous Mesenchymal Component

Malignant chondroid syringoma (MCS; malignant mixed tumour) is a rare neoplasm typically arising on the extremities and trunk. We are report 2 unique cases of MCS, one occurring on the scalp of a 78-year-old man and the other on the trunk of a 72-year-old woman. Both tumours harboured malignant epithelial and malignant mesenchymal components. The latter was represented by liposarcoma in the first case. The malignant components of the second tumour comprised spindle cell squamous cell carcinoma (SCC) and osteosarcoma. Origin from a pre-existing benign chondroid syringoma was clearly evident in both neoplasms. The presence of heterologous malignant mesenchymal components, however, is hitherto unreported in the context of MCS, while a spindle cell SCC component is exceptionally rare. The 2 cases presented herein highlight an expanded morphological spectrum of MCS, with resultant blurring of the boundaries between MCS and cutaneous carcinosarcoma.

Local recurrence of cutaneous mixed tumor (chondroid syringoma) as malignant mixed tumor of the thumb 20 years after initial diagnosis

Benign cutaneous mixed tumor (chondroid syringoma) is the cutaneous counterpart of the benign mixed tumor (pleomorphic adenoma) of salivary glands, consisting of both epithelial and mesenchymal elements. The incidence of cutaneous mixed tumor is rare, composing <0.01% of all primary skin tumors. Herein, we report a case of malignant mixed tumor which recurred in the right thumb 20 years after the reported initial diagnosis of a benign mixed tumor at this site. Histologically, the lesion consisted of highly atypical and infiltrative cells in cords and ductal structures, with an adjacent focus of residual benign mixed tumor present. Perineural invasion of multiple dermal and subcutaneous nerves was also seen. Immunohistochemical staining was strongly and diffusely positive for CK5/6 and p63, with patchy positive S100 and CK7 staining. Wide excision was performed, with no evidence of recurrence or metastasis 5 years later.

Spinal cord compression secondary to metastasis of malignant chondroid syringoma: case report

The authors describe a case of spinal cord compression due to an epidural metastasis of malignant chondroid syringoma. Chondroid syringoma is a rare mixed tumor of the skin composed of both epithelial and mesenchymal elements. Although most are benign, malignant forms have been reported. Malignant chondroid syringoma may progress very slowly and the metastatic spread occurs late, appearing years after the original diagnosis. There is only one other report of spinal cord compression secondary to metastasis of malignant chondroid syringoma, which was finally diagnosed by microscopic examination of an autopsy specimen.

This 63-year-old woman presented with a 4-week history of progressive paraparesis. Admission MRI of the thoracic spine showed an extradural mass arising from the posterior elements and left pedicle of T-9, which caused posterior compression of the spinal cord. Surgical decompression resulted in resolution of the neurological impairments. The histological results were consistent with metastasis of malignant chondroid syringoma. The patient underwent adjuvant radiotherapy and a favorable outcome was noted at the 2-year follow-up visit. This represents the first reported case of spinal cord compression from a metastasis of a malignant chondroid syringoma histologically confirmed in vivo. The authors' experience in this case suggests that resection followed by radiotherapy might be an acceptable means for achieving short-term, progression-free survival.

Siringoma condroide: revisión clínica e histológica de ocho casos

INTRODUCTION

Chondroid syringoma is a rare skin tumor that presents as a slow growing, indolent lesion, that is more frequent in male adults and is usually benign. It is treated surgically and its diagnosis is histological. It can be classified as eccrine and apocrine according to its pathological characteristics.

MATERIAL AND METHODS

Eight cases diagnosed of chondroid syringoma in our Department in the last eight years were reevaluated clinically and histologically and the epiluminiscence microscopy was used in one of them.

RESULTS

Most of the cases occurred as well-defined nodular lesions, whose presumptive clinical diagnosis was adnexal or cystic pathology. All were treated surgically. The epiluminiscence microscopy showed a pattern of homogenous whitish-blue coloring. All the cases had a myxoid matrix and most also had a chondroid one. Five of the eight cases were apocrine, one of them with follicular and sebaceous differentiation.

DISCUSSION

The chondroid syringoma is usually a small-sized skin tumor, frequently on the head and neck. The dermatoscopy does not seem to supply any specific trait to this lesion. The microscopic examination of these lesions reveals tubuloalveolar and glandular type structures positioned as islets within a fibroadipose, chondroid, myxoid or hyaline stroma. The final treatment of these tumors is surgical. As a general rule, it is a benign tumor. Some authors have proposed the term of atypical mixed tumor of the skin for those chondroid syringomas with histological traits of malignancy but without evidence of metastasis.

Chondroid Syringoma

Context.—Chondroid syringoma (CS) is a benign cutaneous adnexal tumor with epithelial and stromal components. Epithelial components derived from folliculo-sebaceous-apocrine germ are evident in apocrine but not in eccrine CS.

Objectives.—To further characterize pilosebaceous differentiation and to identify the presence of Merkel cells in the areas of follicular differentiation.

Design.—Histologic type, folliculo-sebaceous differentiation, character of stroma, and presence or absence of Merkel cells by cytokeratin (CK) 20 immunoreactivity were evaluated in 25 CSs (22 apocrine and 3 eccrine) from the surgical pathology files of Henry Ford Hospital (Detroit, Mich).

Results.—Most CSs occurred in the head and neck region of patients aged 40 years or older. We found no significant difference in sex, age, or location between apocrine and eccrine types. The stroma varied from myxoid (100%) to chondroid (59%), with various amounts of fat (59%) and ossification identified in 2 cases (9%) of apocrine type, but was homogeneously myxoid in the eccrine type. Follicular and sebaceous differentiation was found in 64% and 32% of apocrine CSs, respectively. Only 2 (14%) apocrine CSs with follicular differentiation were positive for CK20 (a few scattered cells in one case and numerous grouped cells in the other in association with follicular epithelium). No correlation was found between type of stroma and the presence of Merkel cells. Scattered Merkel cells were identified in 83% of normal hair follicles and in 33.3% of normal epidermis.

Conclusion.—A high proportion of apocrine CSs show folliculo-sebaceous differentiation. The presence of Merkel cells in foci of follicular differentiation of CS supports the hypothesis that Merkel cells may be an integral constituent of follicles. To our knowledge, the presence of Merkel cells in CS, particularly in proliferative form, has not been described previously in the literature.

Cutaneous myoepithelioma: a clinicopathologic and immunohistochemical study of 14 cases

Analogous to mixed tumors of salivary glands (" pleomorphic adenomas" ), cutaneous mixed tumors (" chondroid syringomas" ) contain a ductal (epithelial) component and a variably prominent myoepithelial component. Tumors showing purely myoepithelial differentiation (myoepitheliomas) have only recently been recognized to arise in the dermis, and to date very few cases have been described. To characterize these tumors further, 14 cutaneous myoepithelial tumors were retrieved from the authors' consult files. Eleven patients were male and 3 were female; their median age was 22.5 years (range, 10 to 63 years), and 7 patients were between 10 and 20 years old. Tumor size ranged from 0.5 to 2.5 cm (mean, 1.1 cm). Most tumors arose on the extremities: 6 on the upper limbs, 6 on the lower limbs, and 1 each on the back and nose. Ten tumors were limited to the dermis, and 5 also extended into superficial subcutis. Thirteen tumors were myoepitheliomas (lacking ductal differentiation), and 1 tumor was a myoepithelial carcinoma (exhibiting severe cytological atypia and a high mitotic rate). Histologically, 7 tumors were solid, composed of ovoid to spindled, histiocytoid, or epithelioid cells with no significant stroma, and 7 were predominantly lobulated, with cords or nests of epithelioid, plasmacytoid, or spindled cells with a variably reticular architecture and a chondromyxoid or collagenous/hyalinized stroma. One tumor was composed solely of plasmacytoid (hyaline) cells, and 1 exhibited extensive adipocytic differentiation. Among the 13 myoepitheliomas, mitoses ranged from 0 to 6 per 10 high-power fields (HPFs) (mean, 1.5); 8 tumors contained no mitoses. The myoepithelial carcinoma had 39 mitoses per 10 HPFs. By immunohistochemistry, all cases were reactive for epithelial markers (keratins and/or epithelial membrane antigen [EMA]); 13 of 14 (93%) expressed S-100 protein, 10 of 11 expressed (91%) calponin, 11 of 14 (79%) expressed EMA, 9 of 14 (64%) expressed keratins, 8 of 14 (57%) expressed smooth muscle actin, 7 of 14 (50%) expressed glial fibrillary acidic protein, 3 of 11 (27%) expressed p63, and 1 of 6 (17%) expressed desmin. All 5 cases without keratin staining were diffusely positive for EMA, and all of these cases showed a solid growth pattern. Follow-up was available for 8 patients (median follow-up, 40 months; range, 6 months to 9 years); 3 tumors (38%) recurred locally, and 1 tumor (13%) also metastasized to the lymph nodes. The case that resulted in recurrence and metastasis had the highest mitotic rate (6 per 10 HPFs) of the cytologically benign tumors. Follow-up information was not available for the myoepithelial carcinoma. This study suggests that approximately 50% of cutaneous myoepitheliomas are distinctive lesions composed of a solid proliferation of cells with abundant eosinophilic syncytial cytoplasm, which often lack immunostaining for keratin, whereas the remainder demonstrate focally reticular architecture and myxoid stroma or plasmacytoid cells, similar to their counterparts in salivary gland and soft tissue. Whereas most cutaneous myoepitheliomas behave in a benign fashion, there is apparently a significant risk for local recurrence but a low metastatic potential.

Malignant Eccrine Acrospiroma with Metastasis to the Parotid

Malignant eccrine acrospiromas are rare. Clinically, they resemble other cutaneous lesions. A high index of suspicion must be maintained in cases of histologically benign eccrine acrospiromas for three reasons: (1) malignant transformation can occur, (2) the presence of both benign and malignant tissue can lead to a false-negative diagnosis if only the benign component is obtained in the biopsy specimen, and (3) benign-appearing tumors can recur locally or metastasize. The primary treatment is wide local excision with or without lymph node dissection. The efficacy of adjuvant chemotherapy and radiation therapy requires further investigation. We describe a case of malignant eccrine acrospiroma in an 80-year-old man, and we review the literature on this tumor, with emphasis on the differential diagnosis.

Atypical mixed tumor of the skin: histologic, immunohistochemical, and ultrastructural features in three cases and a review of the criteria for malignancy

Three cases of cutaneous mixed tumor with atypical features are described. These biphasic tumors comprise cords and nests of often plasmacytoid cells with areas of tubule formation, set in a chondroid stroma. The tumor cells show immunohistochemical positivity for both CAM 5.2 and S-100 and ultrastructural features of myoepithelium. The atypical histological features of an infiltrative margin, satellite tumor nodules, and tumor necrosis, which were present in these cases, have been described in malignant chondroid syringoma; however, a review of the small number of previous case reports demonstrates that histological appearances did not always correspond with apparent malignant potential in this tumor. The term atypical mixed tumor is recommended for tumors in which there are histological features of malignancy, especially local invasion, without proven metastases. Complete excision of the tumor and careful follow-up are advised, as at present the malignant potential of these tumors cannot be reliably predicted from their histological appearance.

Mixed tumors and myoepitheliomas of soft tissue: a clinicopathologic study of 19 cases with a unifying concept

We report 19 unusual cases of mixed tumors and myoepitheliomas arising in soft tissues. The neoplasms occurred in 12 males and seven females. The age at diagnosis ranged from 2 to 83 years (mean 35, median 30). Eight tumors arose in the upper limb, six in the lower limb, three in the trunk, and two in the head and neck region. Three cases involved both dermis and subcutis; the remainder arose in subcutaneous (13 cases) or deep subfascial soft tissue (three cases). The most common presenting complaint was a painless swelling, with duration ranging from 2 weeks to 1 year (median 2.5 months). Microscopically, the tumors were predominantly well circumscribed and lobulated. Six cases showed a focally infiltrative margin. Cardinal morphologic features included nests, cords, and ductules of epithelioid cells and/or nests of spindled cells within a hyalinized to chondromyxoid stroma. One tumor was predominantly composed of myoepithelial cells and devoid of epithelial differentiation (i.e., ductules). Cytoplasmic hyaline inclusions were noted in two cases; squamous differentiation was seen in one case. Osteoid production and/or metaplastic bone was observed in three tumors. Chondroid differentiation (usually mature) was seen in four cases. Adipocytic differentiation was seen in two tumors. Mitotic activity was variable but generally scant; atypical mitotic figures were not identified. By immunohistochemistry, 16 of 16 cases expressed pan-keratin; 16 of 17 S-100 protein; six of 14 alpha smooth muscle actin (IA4); two of 10 muscle specific actin (HHF-35); two of 10 desmin; three of 11 glial fibrillary acidic protein; and three of 16 epithelial membrane antigen. Clinical follow-up was available in 10 patients and ranged from 6 months to 20 years (mean 4.25 years, median 2 years). Two patients developed local recurrence; metastasis to lung and lymph nodes were observed in two additional patients. Both of the latter patients died. We believe that these findings expand the concept of cutaneous mixed tumors to include neoplasms composed predominantly of myoepithelial cells and to include tumors arising in deeper subcutaneous and/or subfascial tissues. The clinical behavior of such neoplasms, when arising in soft tissues, may be difficult to predict but is most often benign; however, a minority of lesions metastasize. Until larger studies with longer follow-up are available, treatment and prognostication are probably best based on criteria used in comparable salivary gland tumors.