Atypical Immunohistochemical Features Research Articles

Lipoblastoma of the lip.

Lipoblastomas are benign tumors arising from embryonic white fatty cells that continue to proliferate and develop during the postnatal period. It commonly affects children 3 years of age or younger, with the neck being the most frequent site in the head and neck region. Only 10% of cases are seen at 10 years or above. The etiopathogenesis of lipoblastomas is linked to polysomy and rearrangement of chromosome 8q11-13 with or without the involvement of the pleomorphic adenoma gene 1 (PLAG1) gene. Here, we report one of the first cases of lipoblastoma of lip in a 10-year-old boy with atypical immunohistochemical features and the need for thorough clinical and histopathological evaluation of cases with atypical findings. The novel pathogenetic mechanism of lipoblastoma from the cluster of differentiation 34-positive (CD34+) stem cells has also been discussed.

Liver metastatic basaloid squamous cell carcinoma with negative expression of pancytokeratin: a case report and literature review

BackgroundBasaloid squamous cell carcinoma (BSCC) is a rare subtype of squamous cell carcinoma with a high rate of distant metastasis. BSCC occurs most commonly in the esophagus, lungs, and head and neck. However, BSCC occurring in an atypical site without a known primary tumor and/or with the presence of atypical immunohistochemical features can result in delayed diagnosis or misdiagnosis.Case presentationHere, we report a case of a 67-year-old man with liver metastatic BSCC with negative pancytokeratin (AE1/AE3) expression. He presented with a chief complaint of epigastric discomfort. Imaging examination revealed a subcapsular mass in the right anterior lobe of the liver. Then, the patient underwent an irregular right hepatectomy. Grossly, the mass was gray, with a size of 7 × 7 × 4 cm. Microscopically, the mass comprised epithelioid tumor cells with both solid and pseudoadenoid structures, accompanied by necrosis. Immunohistochemical staining showed that the tumor cells were negative for AE1/AE3, CK18, CK7, CK19, Hepatocyte Paraffin-1, Glypican-3, Arginase-1, CD56, Chromogranin A, Synaptophysin, Vimentin, and Carcinoembryonic antigen. The Ki-67 index was 80%.The mass was diagnosed as a malignant tumor but could not be classified further. One month after surgery, the patient’s reexamination revealed esophageal tumor, and biopsy revealed BSCC. The slides of the liver tumor were reviewed, and the morphology was similar to that of the esophageal tumor. Moreover, supplementary immunohistochemical staining of liver tumor indicated p63 and p40 were strongly positive, that confirmed the liver tumor was metastatic BSCC. Previous studies have reported that 3.7% of esophageal BSCCs did not express AE1/AE3.ConclusionWhen a malignant tumor comprises epithelioid cells with solid and/or pseudoadenoid structures, but not adenocarcinoma or neuroendocrine carcinoma, even if the tumor cells are negative or weakly positive for AE1/AE3, we should consider BSCC. For a definite diagnosis, immunohistochemical staining for squamous cell carcinoma markers, including p63 and p40, and examination of common primary sites of BSCC should be performed.

Nuclear protein in testis carcinoma of the mediastinum: a case report

BackgroundNuclear protein in testis carcinoma is a rare and very aggressive undifferentiated cancer which characteristically arises in the midline of the head, neck, and mediastinum.Case presentationWe describe the case of a 46-year-old white woman admitted for superior vena cava syndrome revealing a mediastinal tumor. Pathological examination of specimens obtained by mediastinoscopy revealed an undifferentiated tumor with solid growth and positive immunoreactivity for p40 and negative immunoreactivity for cytokeratin markers. Immunohistochemical staining was positive for nuclear protein in testis, allowing the diagnosis of nuclear protein in testis midline carcinoma of the mediastinum.ConclusionsWe present a rare case of mediastinal nuclear protein in testis carcinoma with diagnosis based on nuclear protein in testis protein positivity and atypical immunohistochemical features including p40 positivity and anti-cytokeratin negativity. Physicians must remain aware of the possibility of nuclear protein in testis carcinoma especially in young patients with thoracic symptoms and suspicion of neoplasm.

PNET with neuroendocrine differentiation of the lung

Ewing’s sarcoma/primitive neuroectodermal tumor (PNET) has been the subject of recent reports describing morphologic variants (adamantinoma-like, large cell, spindle cell, sclerosing, clear cell, and vascular-like) of the most classic form, as well as cases displaying unusual morphologic differentiation and atypical immunohistochemical features. We report a case of an uncommon lung tumor in a 20-year-old female, morphologically and molecularly consistent with an Ewing’s sarcoma/PNET tumor with foci of squamous differentiation, and peculiar expression of vimentin, high-molecular-weight keratins, p63, synaptophysin, and chromogranin. This case raises a challenging differential diagnostic problem with therapeutic implications: Should the patient be treated following the protocols for Ewing’s sarcoma/PNET tumors or as for lung carcinoma with neuroendocrine features? The patient we report here was treated with neoadjuvant chemotherapy for Ewing’s sarcoma/PNET according to Euro Ewing 99 study protocol followed by surgery and has no evidence of disease 15 months after the initial diagnosis. This highlights the importance of achieving the correct diagnosis of these atypical tumors using all clinical, morphological, and ancillary methods available to allow for their correct and timely treatment.