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Presented by Dr. Cimino-Mathews and prepared by Dr. Austin McCuiston
Clinical history: 30 year-old female with rectal bleeding.
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Clinical history: 30 year-old female with rectal bleeding
Correct
Answer: Primary anorectal melanoma
Histology: The excisional specimen contains a mass centered in the anorectal mucosa that is comprised of atypical spindle cells arranged in nests and intersecting fascicles. The lesional cells contain elongated nuclei with fairly evenly dispersed chromatin, occasional binucleation, occasional intranuclear inclusions, and a brisk mitotic rate. There is no associated in situ component. Immunostains show the lesional cells to be diffusely positive for S100 protein and negative for AE1/AE3.
Discussion: Mucosal melanomas are rare but can occur in mucosal sites throughout the body, including at the anorectal junction. Melanomas of any body site can have varied histologic appearances, ranging from epithelioid “pink cell” tumors with prominent nucleoli to spindle cell tumors, thus the differential diagnosis can be broad and varied depending upon the organ site and the morphology. In the gastrointestinal tract, it is useful to think of the differential diagnosis of spindle cell tumors in the context of the “layer” of the wall. Spindle cell lesions that are centered in the mucosal layer (such as this tumor) include mucosal melanoma, benign fibroblastic polyp/perineurioma, some benign nerve sheath tumors, leiomyomas of the muscularis mucosa, and rarely synovial sarcomas. In contrast, inflammatory fibroid polyps are centered in the submucosa; gastrointestinal stromal tumors (GIST), most schwannomas, leiomyomas, glomus tumors and clear cell sarcomas are centered in the muscularis propria; and inflammatory myofibroblastic tumors, fibromatosis, and sclerosing diseases are centered in the subserosa/mesentery. Metastatic lesions from other organ sites can involve any layer. Recognizing the morphologic features of the lesions and the layer of the gastrointestinal tract involved, along with performing a targeted immunopanel and knowing the clinical history, can enable accurate diagnosis.
Reference(s): (if available, if not, do not include)
– Voltaggio L, Montgomery EA. Gastrointestinal tract spindle cell lesions–just like real estate, it’s all about location. Mod Pathol. 2015 Jan;28 Suppl 1:S47-66.Incorrect
Answer: Primary anorectal melanoma
Histology: The excisional specimen contains a mass centered in the anorectal mucosa that is comprised of atypical spindle cells arranged in nests and intersecting fascicles. The lesional cells contain elongated nuclei with fairly evenly dispersed chromatin, occasional binucleation, occasional intranuclear inclusions, and a brisk mitotic rate. There is no associated in situ component. Immunostains show the lesional cells to be diffusely positive for S100 protein and negative for AE1/AE3.
Discussion: Mucosal melanomas are rare but can occur in mucosal sites throughout the body, including at the anorectal junction. Melanomas of any body site can have varied histologic appearances, ranging from epithelioid “pink cell” tumors with prominent nucleoli to spindle cell tumors, thus the differential diagnosis can be broad and varied depending upon the organ site and the morphology. In the gastrointestinal tract, it is useful to think of the differential diagnosis of spindle cell tumors in the context of the “layer” of the wall. Spindle cell lesions that are centered in the mucosal layer (such as this tumor) include mucosal melanoma, benign fibroblastic polyp/perineurioma, some benign nerve sheath tumors, leiomyomas of the muscularis mucosa, and rarely synovial sarcomas. In contrast, inflammatory fibroid polyps are centered in the submucosa; gastrointestinal stromal tumors (GIST), most schwannomas, leiomyomas, glomus tumors and clear cell sarcomas are centered in the muscularis propria; and inflammatory myofibroblastic tumors, fibromatosis, and sclerosing diseases are centered in the subserosa/mesentery. Metastatic lesions from other organ sites can involve any layer. Recognizing the morphologic features of the lesions and the layer of the gastrointestinal tract involved, along with performing a targeted immunopanel and knowing the clinical history, can enable accurate diagnosis.
Reference(s): (if available, if not, do not include)
– Voltaggio L, Montgomery EA. Gastrointestinal tract spindle cell lesions–just like real estate, it’s all about location. Mod Pathol. 2015 Jan;28 Suppl 1:S47-66.
