Case of the Month

A 62-year-old-man resents for the evaluation of a painless nodule under his nose that has been enlarging over the past 3 years. No history of cutaneous malignancy.

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Diagnosis: Chondroid Syringoma (Mixed Tumor of the Skin)

Discussion and Reference (from VisualDx.com, Dr. Crutchfield is one of the Dermatology editors)

Chondroid syringoma

Contributors: Gil Weintraub MD, Noah Craft MD, PhD, Belinda Tan MD, PhD, Lowell A. Goldsmith MD, MPH

Synopsis

Chondroid syringoma, or mixed tumor of the skin, is a rare benign tumor of the sweat glands. The term mixed tumor refers to the presence of epithelial and mesenchymal elements derived from either eccrine or apocrine glandular tissue.

Chondroid syringomas present as small (0.5-3 cm), painless, slow-growing masses in the head and neck region. They are typically solitary dermal or subcutaneous nodules found in middle-aged men, although cases of multiple tumors, larger tumors, and tumors in various locations, across ages, and in both sexes have been reported.

Malignant transformation of mixed tumors of the skin is very rare. Malignant forms tend to grow rapidly and occur more commonly on the lower extremities of younger females. Metastasis to regional lymph nodes, bone, and visceral organs may occur.

Chondroid syringomas are rare, representing less than 0.1% of cutaneous tumors. Given their low rate of incidence and nonspecific clinical presentation, they are rarely a preoperative diagnosis of skin tumors. Definitive diagnosis requires total excision and histopathologic examination.

Codes

ICD10CM:
D23.9 – Other benign neoplasm of skin, unspecified
SNOMEDCT:
302828001 – Syringoma of skin

Look For

A solitary, firm tumor in the head or neck region with minimal overlying skin change that grows slowly over the course of years. The mass is often small, ie, less than 3 cm in diameter.

Chondroid syringomas are typically found on the nose, cheek, upper lip, scalp, forehead, and chin. Less common sites include the trunk, extremities, scrotum, and eyelid.

Diagnostic Pearls

Chondroid syringomas will have a high degree of keratinization and eccrine / apocrine differentiation on histology, distinguishing them from mixed tumors of salivary glands.

Differential Diagnosis & Pitfalls

• Pleomorphic adenoma – Common, benign mixed tumor of salivary glands that can develop in all major and minor salivary glands.
• Epidermoid cysts – Benign cysts commonly on the face, trunk, extremities, mouth, or genitals. Often dome shaped with a punctum and expressible cheesy material.
• Lipoma – Benign, slow-growing soft tissue tumor of white fat cells that often appears on the neck, trunk, extremities, and buttocks. Nontender, mobile, solitary or multiple and usually occurs between the fourth and seventh decades of life.
• Neurofibroma – These asymptomatic skin-colored or violaceous nodules can arise anywhere on the body, most commonly on the head, neck, and upper trunk. When compressed, the buttonhole sign is a strong diagnostic clue.
• Dermoid cyst – Present at birth, these appear on the head, commonly along the lateral eyebrow.
• Dermatofibroma (histiocytoma) – A common, benign skin tumor that is often present on the extremities. Squeezing laterally on nodules will pucker skin inward in a characteristic dimple, or Fitzpatrick's sign.
• Pilar cyst – Common, benign cysts of hair follicular origin that present on the scalp. Firm, smooth, and mobile, there are often multiple cysts, and they may rupture and extrude their contents or form cutaneous horns.
• Abscess – Erythema, induration, and discomfort are often present.

Best Tests

Clinical presentation is nonspecific, and diagnosis requires biopsy and histopathologic examination.

Histopathology Findings:

Common features

• Well-circumscribed, nodular or multinodular, biphasic dermal tumor
• Epithelial component is composed of ductal / glandular structures lined by a bilayer of cuboidal cells and solid cellular aggregates without glandular formation
• Solid aggregates contain cells with abundant eosinophilic cytoplasm and an epithelioid to plasmacytoid morphology (myoepithelial cells) · Stromal component can be myxoid, chondroid, fibrous, or a combination of these

Occasional features

• Follicular, matrical, sebaceous, or adipose differentiation
• Calcification or ossification · Pronounced dilation of epithelial ducts
• Eosinophilic globules in the ductal lumina (collagenous spherulosis)
• Solid islands of squamous epithelium
• Keratinous cysts

Note: Increased cytologic atypia, mitotic figures, necrosis, and infiltrating margins are all suggestive of malignant transformation.

Management Pearls

Wide surgical margins that include a cuff of normal tissue are preferred over simple removal of the lesion. Incomplete excision causes risk of recurrence of tumor.

Therapy

The treatment of choice is complete excision of the tumor including a margin of normal skin allowing histopathologic examination of tumor features.

Other methods of removal are not recommended, as they do not allow for microscopic diagnosis and confirmation of clear margins, but include:

• Electrodessication
• Dermabrasion
• Vaporization with argon or CO2 laser

References

Constantinescu MB, Chan JB, Cassarino DS. Chondroid syringoma with tyrosine crystals: case report and review of the literature. Am J Dermatopathol. 2010 Apr;32(2):171-4. PubMed ID: 19851085

Yavuzer R, Başterzi Y, Sari A, Bir F, Sezer C. Chondroid syringoma: a diagnosis more frequent than expected. Dermatol Surg. 2003 Feb;29(2):179-81. PubMed ID: 12562350

Satter EK, Graham BS. Chondroid syringoma. Cutis. 2003 Jan;71(1):49-52, 55. PubMed ID: 12553630

Sheikh SS, Pennanen M, Montgomery E. Benign chondroid syringoma: report of a case clinically mimicking a malignant neoplasm. J Surg Oncol. 2000 Apr;73(4):228-30. PubMed ID: 10797337

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