Sebaceous Gland Differentiaton

Sebaceous carcinoma arises from meibomian (51%) and Zeis glands (10%) of the eyelid. The tumor is not caused by ultraviolet (UV) radiation but certain HPVs and ionizing radiation are contributing factors. Chronic chalazion is also a predisposing factor due to inflammation and production of oleic acid. Sebaceous carcinoma may occur singly or in association with keratoacanthomas and internal (GI tract) malignancies as part of the Muir-Torre syndrome (199). Sebaceous carcinoma affects women more than men, usually in the sixth or seventh decade of life. It predominates in Asians. Approximately 25% of cases are extraocular, mostly from the parotid gland (20%). A multicentric origin is reported in 12% of cases. Clinically, the lesions present as yellowish nodules of variable size. Histopathological examination shows lobules and cords of neoplastic cells with sebaceous differentiation. Cells have a foamy cytoplasm, nuclear pleomorphism, and mitotic figures. A pagetoid pattern is observed in 40-80% of cases. IHC stains are positive for EMA, but are negative for CEA, breast carcinoma antigen, S-100, or GCDFP-15. Stains for lipids are useful, including Sudan IV and oil red 0. Surgical excision is the treatment of choice but the recurrence rate is 30%. Mohs' surgery is indicated for tissue preservation and better margin control (200). Recurrence rates are lower but the pagetoid pattern and multicentric origin impair the effectiveness of the Mohs' technique. Metastases occur in 14-25% of cases, mostly to lymph nodes, liver, lungs, bones, and brain. Nodal disease is treated with surgical excision of the primary site, lymph node dissection, and radiation therapy. Distant metastatic disease is managed with surgery, radiation and chemotherapy.

Initial work-up includes physical examination, rectal and breast examination, ophthalmological evaluation, stool guaiac, complete blood count (CBC), chest -g x-ray, mammography, and colonoscopy. Follow-up is done at 1 and 3 months after surgery; every 3 months for 2 years; and yearly thereafter. £

Merkel Cell Carcinoma a

Merkel cell carcinoma originates in Merkel cells (cutaneous mechanoreceptors that provide a template for nerve arborization during neural development). It is an infrequent tumor with unknown incidence. Men and women are equally affected and patients' mean age is 69 years. UV radiation, immunosuppression, @

and glucocorticosteroids are relevant contributing factors. Merkel cell carcinoma (MCC) presents as an asymptomatic, erythematous-violaceous nodule with telangiectasias (Fig. 33). It may resemble BCC, SCC, or MM, and is usually less than 2 cm in diameter. Approximately 50% of lesions affect the head and neck followed by the extremities in 35% of cases (201). Histological examination shows monotonous small cells with round nuclei, marked mitotic activity, and prominent nucleoli. Histologically, MCC resembles undifferentiated small-cell carcinoma. IHC staining is positive for neuron-specific enolase, neurofilament and CK. Localized disease is best approached with surgical excision using 3 cm margins or Mohs' micrographic surgery (202). Overall, cure rates are 60-90% for primary and 50% for recurrent lesions. Primary tumors of the head and neck, however, have a recurrence rate of 20-100% after surgery alone, and various centers advocate adjuvant external beam radiation therapy. This approach reduces recurrence rates to 10-40%. Initial workup should include physical examination with detailed node evaluation, CBC, LFT's, and chest radiographs. CT scans of the chest, neck, abdomen, and pelvis are also

Figure 33 Large, nonspecific, ulcerated nodule on the cheek of an elderly women. The biopsy showed Merkel cell carcinoma and the patient was treated with Mohs' surgery.

indicated. Nodal disease occurs in approximately 50% of patients; therefore, a sentinel node biopsy is recommended for most lesions. Survival is only 48% after surgical excision, therapeutic node dissection, and radiotherapy (203). Distant metastatic disease may involve the skin, lungs, liver, and brain. Combination chemotherapy is palliative and all patients eventually die from their disease within 6 months.

How To Reduce Acne Scarring

How To Reduce Acne Scarring

Acne is a name that is famous in its own right, but for all of the wrong reasons. Most teenagers know, and dread, the very word, as it so prevalently wrecks havoc on their faces throughout their adolescent years.

Get My Free Ebook


Post a comment