Similar scalp nodules in two female patients

CASE #1

The patient was a a 46-year-old woman who presented with a nodule on her scalp. The nodule, which had been increasing in size, was not pruritic or painful. It had appeared six months earlier and was a recurrence of a lesion that had been removed several years ago. The patient reported no family history of similar nodules. A review of systems and lymph node examination were negative. The patient denied any recent weight loss. She was not taking any medications.

CASE #2

A 64-year-old woman presented with a growing nodule on her scalp. The nodule had first appeared approximately two months earlier. The woman noted slight pain, but the nodule was otherwise asymptomatic. She reported no other health problems, although she had recently experienced unintentional weight loss. A lymph node examination was negative. The patient reported no personal or family history of similar nodules. She was not taking any medications.

CASE #1: Cylindroma

A cylindroma is a benign neoplasm of adnexal origin. The lesion's precise origin is a matter of debate; sometimes cylindromas are considered eccrine in origin, but most often, they are thought to be of apocrine derivation.

Cylindromas can occur singly (as was the case in our patient), but they can also present as multiple nodules. The most common location is the head and neck area, particularly the scalp, but other locations, such as the trunk or genitalia, have been reported. Cylindromas are more commonly seen in females than males. When multiple cylindromas form on the scalp, they can coalesce and create an appearance that has been referred to as a “turban” tumor. No clinical features are considered pathognomonic of a cylindroma, and oftentimes, the diagnosis is made after biopsy.

Multiple cylindromas can be seen in Brooke-Spiegler syndrome, an autosomal dominant condition caused by a defect in the CYLD gene, a negative regulator of nuclear factor-kB signaling. In Brooke-Spiegler syndrome, cylindromas occur in association with trichoepitheliomas and spiradenomas.

Another disorder with multiple cylindromas is Rasmussen syndrome. This autosomal dominant condition consists of multiple cylindromas, trichoepitheliomas, and milia.

When subjected to pathologic examination, cylindromas have a distinctive appearance: Sharply circumscribed basaloid nodules are closely apposed in a pattern described as “jigsaw puzzlelike.” A rim of eosinophilic, basement membranelike material that stains positive for periodic acid-Schiff (PAS) surrounds each of the basaloid nests. In addition, the basaloid nests frequently contain eosinophilic droplets, which also stain positive for PAS.

Treatment consists of complete excision of the tumor. Although our patient had experienced recurrence after the initial tumor was removed, recurrence is uncommon. The tumor was excised, with good results.

CASE #2: Merkel cell carcinoma

Also known as trabecular cell carcinoma or cutaneous neuroendocrine carcinoma, Merkel cell carcinoma (MCC) is a malignant neoplasm most likely of neuroectodermal origin. The Merkel cell is a mechanoreceptor that resides in the basal layer of the epidermis. Controversy exists, and MCC may have no relation to Merkel cells. MCC is highly aggressive, so early recognition and therapy are important.

Clinically, MCC presents as a rapidly growing red nodule, usually on the head or neck but sometimes on the extremities or buttocks. The tumor most commonly occurs in patients older than 50 years and shows no gender preference. Approximately one-third of patients have regional lymph-node involvement at presentation. Distant metastases are seen in 40% of patients. The five-year survival rate is 64%.

MCC is a poorly defined dermal tumor that often infiltrates the subcutaneous fat. The cells are monotonous, small, and round, with a distinctive smudged chromatin pattern. Usually arranged in sheets, cells can also be arranged in nests and trabeculae. Positive perinuclear staining of cytokeratin 20 and cytokeratin CAM 5.2 is characteristic. MCC cells resemble those of other neuroendocrine tumors, such as small cell lung carcinoma, but thyroid transcription factor 1 helps differentiate these two, staining positive in cutaneous metastases from small cell lung carcinoma and negative in MCC.

Stage 1 MCC is defined as localized disease; treatment comprises surgery with wide, 3- to 5-cm local margins, sentinel lymph node biopsy, and radiotherapy. Stage 2 MCC has regional lymph-node metastases and requires surgery, radiotherapy, and chemotherapy. Stage 3 is disseminated disease and should be treated with chemotherapy.

Our patient was sent to a Mohs surgeon for excision.

Dr. Yang is assistant professor of dermatology at Baylor College of Medicine in Houston.