Pancreatic Endocrine Heterotopia Involving Meckel's Diverticulum: A Potential Mimic of Neuroendocrine Tumor.

Pancreatic heterotopia most commonly occurs in the upper gastrointestinal tract, but can occur in other sites, including Meckel's diverticulum. When multiple histologic elements of the pancreatic tissue (acini, ducts, and endocrine cells) are present, the diagnosis is typically straightforward. In this article, we report a rare case of pure endocrine pancreatic heterotopia involving a Meckel's diverticulum, a potential mimic of a well-differentiated neuroendocrine tumor. Several features were useful in making the distinction, including lack of desmoplasia and mass forming lesion, and immunohistochemical staining in a physiological pattern similar to that of islets of Langerhans. It is important for pathologists to be aware of this entity and its features to avoid misdiagnosis of a neuroendocrine tumor.

Giant Dermatofibrosarcoma Protuberans With Bilateral Orbital Involvement.

Dermatofibroma sarcoma protuberans (DFSP) is a rare, locally aggressive soft tissue sarcoma with a tendency for recurrence after excision. Although reports of unilateral orbital and bilateral eyelid disease exist, there have been no prior reports of DFSP with bilateral orbital involvement and no previously described cases of DFSP associated with transient optic neuropathy. The authors present a case report of a 34-year-old woman with a giant scalp DFSP involving the bilateral orbits. Despite radical resection with 5 cm margins where possible, multiple positive margins remained including deep positive margins at the bilateral superomedial retroseptal soft tissue. The patient completed adjuvant radiation for surgically unresectable disease. This case highlights the challenge of achieving local control given the disease extent and infiltration of the bilateral eyelids and orbits. This is the first reported case of DFSP with bilateral orbital involvement and associated transient optic neuropathy.

Pure mucinous (colloid) adenocarcinoma of the conjunctiva.

Primary mucinous carcinomas of the periorbital region are very rare and often require differential diagnosis of metastatic disease. We describe a case of pure mucinous adenocarcinoma arising in the subconjunctival stroma of the ocular fornix in a female patient with a longstanding history of bilateral ocular cicatricial pemphigoid. Histologically, the tumor was composed of predominantly goblet-like cells floating in pools of mucin separated by delicate collagenous septa. The initial suspicion was of primary cutaneous mucinous carcinoma and less likely endocrine mucin-producing sweat gland carcinoma, however the CK7-/synaptophysin-/chromogranin-immunoprofile did not confirm either of the two. Focal areas of the tumor demonstrated peripheral staining for p63 and CK5/6 suggestive of an in situ component. Additional studies showed that the tumor cells were positive for CK20, CDX2, villin and MUC2. Given the final immunophenotype of the tumor, metastatic lesion from the lower gastrointestinal tract had to be ruled out. Thorough clinicoradiological work-up did not reveal any other primary tumors or evidence of metastatic disease elsewhere. Unique histomorphology, the presence of an in-situ component and negative clinical investigation suggest that this is a primary mucinous adenocarcinoma arising in the ocular fornix. This case may represent the first report of this entity in the literature.

Metastatic sarcomatoid renal cell carcinoma manifesting as a subcutaneous soft tissue mass.

Metastases from visceral malignancies to subcutaneous soft tissues are relatively rare and their diagnosis requires a high level of suspicion. It is even more challenging if a metastatic lesion shows non-specific high-grade spindle cell morphology overlapping with various primary cutaneous and soft tissue tumors. We describe a unique case of subcutaneous metastasis of sarcomatoid renal cell carcinoma which was the first manifestation of the occult malignancy. The patient had a history of lipomas and dysplastic nevi and presented with an upper back mass. The mass, located superficially within the subcutis, was composed of atypical spindle cells arranged in a storiform pattern. By immunohistochemistry, the tumor cells were strongly diffusely positive for cytokeratin AE1/AE3 and vimentin and negative for Melan-A, S-100 protein, SOX10, melanoma cocktail, epithelial membrane antigen (EMA), p63, CK7, CK18, CK20, smooth muscle actin (SMA), desmin, CD34, TTF-1, CD21, CD99 and bcl-2. Scattered tumor cells were positive for MDM2 immunostain, but MDM2 amplification was not detected using fluorescent in situ hybridization (FISH). Co-expression of cytokeratin and vimentin by the tumor raised the possibility of metastatic renal cell carcinoma and positivity of the tumor for PAX8 supported this hypothesis. A large renal mass was detected radiologically and the subsequent nephrectomy specimen showed high-grade clear cell renal cell carcinoma with sarcomatoid features.

Circulating Breast Carcinoma Cells Mimicking Therapy-Related Acute Myeloid Leukemia.

Circulating tumor cells are rare in peripheral blood smears. We report the case of a patient with circulating breast carcinoma cells resembling circulating myeloid blasts and provide a brief review of the literature. Peripheral blood smears and a bone marrow aspirate were examined morphologically and by flow cytometry and fluorescence in situ hybridization (FISH). Bone marrow histology in conjunction with immunohistochemical stains was also evaluated. A population of atypical cells with blast-like morphology was present in the peripheral blood. Flow cytometry showed a 9% population of CD45 dim positive, CD13 partial positive, and CD15 variably positive cells. Peripheral blood FISH analysis revealed deletion 7q, gain of 8q, and deletions 16q and 17q in 32.5% to 36% of 200 interphase cells analyzed. The bone marrow biopsy showed cohesive groups of cytokeratin AE1/AE3 positive cells. Our report demonstrates that circulating carcinoma cells can mimic a high-grade myeloid neoplasm morphologically and by flow cytometry and FISH analysis.