Primary Malignant Melanoma of the Esophagus With Separate Foci of Melanoma In Situ and Atypical Melanocytic Hyperplasia in a Patient Positive for Human Immunodeficiency Virus: A Case Report and Review of the Literature

Archives of Pathology & Laboratory Medicine, Oct 2008 by Fredricks, Jennifer Rose Chapman, Bejarano, Pablo A

Primary malignant melanoma of the esophagus (PMME) is a rare neoplasm. The primary nature of esophageal melanoma has been questioned in the past because most reported cases have not been able to demonstrate local tumorigenesis or evolution of the malignancy from a preceding benign lesion or cell. In addition, the occurrence of metastatic melanoma to the esophagus is much more common than PMME.We report a case of PMME with separate foci of melanoma in situ and atypical melanocytic hyperplasia in a patient with human immunodeficiency virus infection. To our knowledge, this is the first reported case of PMME in a patient with a previous diagnosis of human immunodeficiency virus infection. In addition to adding data to the limited literature on this subject, we also provide histologic evidence that demonstrates the primary nature of some esophageal melanomas. This case also documents the occurrence of PMME in a patient positive for human immunodeficiency virus. We also provide a review of the relevant literature.

(Arch Pathol Lab Med. 2008;132:1675-1678)

Primary malignant melanoma of the esophagus (PMME) is an extremely rare neoplasm representing 0.1% to 0.2% of all primary esophageal cancers.1 To date, there are fewer than 300 cases reported in the world's literature. Despite the growing number of reported cases, the exact histogenesis of this primary malignancy remains elusive. It is believed that the presence of increased melanoblasts within the basal layers of the squamous mucosa may predispose to subsequent development of melanoma. To further elucidate the subject, we present a case of PMME with associated junctional activity and separate foci of atypical melanocytic hyperplasia, melanoma in situ, and early invasive malignant melanoma in a patient with a longstanding diagnosis of human immunodeficiency virus (HIV) infection. To our knowledge, only 1 other case has been reported in the literature that demonstrated the entire progression of disease from benign melanocytic hyperplasia to atypical melanocytic hyperplasia to melanoma in situ in association with an invasive melanoma.2 Additionally, our search of the literature revealed no other reported cases of PMME in an HIV-positive patient. In addition to adding data to the limited reports of PMME, this case provides additional evidence about the primary nature of the disease and its evolution from melanocytic hyperplasia of the esophagus. This case also documents the occurrence of PMME in a patient previously diagnosed with HIV.

REPORT OF A CASE

The patient is a 60-year-old, Hispanic man, with a medical history of HIV diagnosed in 1996, who presented to his primary care physician complaining of 2 months of progressive dysphagia for solids. The patient had no other medical or surgical history but did have a smoking history of 20 pack-years, although he stated that he had not smoked for the past 10 years. The patient underwent an upper endoscopy, which revealed a 6-cm, lobulated, and pigmented mass located in the distal esophagus. Biopsy of this mass confirmed the diagnosis of malignant melanoma. The patient had no known history of cutaneous, mucosal, or ocular melanoma, and a physical examination was unremarkable. The patient underwent a transhiatal esophagectomy for primary resection. The postoperative course was uncomplicated, and the patient was discharged home.

PATHOLOGIC FINDINGS

Gross Description

The surgical specimen consisted of a segment of distal esophagus with an attached portion of proximal stomach. The esophagus measured 12 cm in length and 5.5 cm in circumference. The stomach measured 9.5 cm in length and 11.5 cm in circumference. Located 1.5 cm proximal to the gastroesophageal junction was a 5.5-cm polypoid and dark-brown mass projecting from the underlying squamous mucosa (Figure 1). The lesion was friable and irregularly lobulated. Located 0.3 cm proximal to this lesion was a second pigmented nodule, which measured 0.9 cm and was flat. A third lesion was located 4.0 cm proximal to the main mass, measured 0.3 cm, and was flat.

Histology and Immunohistochemistry

Microscopically the main mass was composed of large, bizarre, and pleomorphic cells with abundant cytoplasmic melanin pigment. The nuclei were large and irregularly shaped with prominent nucleoli. The tumor cells reached the submucosa and focally reached the underlying muscularis propria. Vascular invasion was identified. The tumor cells were diffusely positive for S100 protein and HMB-45 (Figure 2, a through c). Fifteen lymph nodes were examined, and metastatic tumor was identified in 2 (13.3%) of 15 lymph nodes.

A separate focus of early invasive malignant melanoma was identified 0.3 cm proximal to the main mass. This lesion was accompanied by melanoma in situ as well as junctional activity of the basal melanocytes and was separated from the main mass by unremarkable squamous mucosa (Figure 3). The third pigmented lesion, which was located 4 cm proximal to the main mass, contained atypical melanocytic hyperplasia and melanoma in situ (Figures 1 and 4).