Ernesto Martinez Duarte

We report a bronchiolar adenoma of the lung with unusual features. A 68-year-old woman presented with a right lower lobe lung mass found during routine screening. Positron emission tomography studies revealed a metabolically active 5.4 cm lesion. The patient underwent an endoscopic ultrasound-guided transbronchial fine needle aspiration. The cytologic material was interpreted as a basaloid neoplasm of uncertain malignant potential; focally, the cytologic features resembled adenoid cystic carcinoma. A lobectomy revealed a circumscribed biphasic tumor, composed of luminal epithelial cells and subjacent basal cells. The luminal cells consisted of ciliated cells and type II pneumocytes expressing CAM 5.2, TTF1, and NAPSA (napsin A aspartic peptidase). The basal cells were associated with a weakly basophilic matrix and basement membrane-like material; these cells expressed TP63 and expressed weakly with CAM 5.2 and calponin (CNN1). The tumor did not invade the pleura and did not show vascular or perineural invasion. The histopathologic and immunohistochemical findings, as well as the BRAF- V600E mutation supported its classification as an unusual variant of bronchiolar adenoma showing a prominent basement membrane-like material. This tumor was incidentally associated with a lung adenocarcinoma in situ. This presentation describes an unusual variant of bronchiolar adenoma and underscores the value of integrating the cytologic, histologic, and molecular findings.

Background: Mucoepidermoid carcinoma is the most common malignant neoplasm arising from the salivary glands (Ali et al. in J Ayub Med Coll Abbottabad 20(2): 141-2, 2008, Xi et al. in World J Surg Oncol 10: 232, 2012). When arising from anatomic sites other than the salivary glands it can be a diagnostic challenge. Primary and metastatic mucoepidermoid carcinoma from and to the pleura are extremely rare entities that are frequently misdiagnosed as adenocarcinoma, adenosquamous carcinoma, or squamous cell carcinoma (Xi et al. in World J Surg Oncol 10: 232, 2012). Case presentation: We describe an unusual case of a 64-year-old Caucasian female patient with metastatic high-grade mucoepidermoid carcinoma to the pleura, morphologically resembling squamous cell carcinoma. Molecular studies of both the parotid gland and pleural tumors helped prove the metastatic nature of the pleural lesion. Conclusions: Metastatic mucoepidermoid carcinoma to the pleura is a rare entity, frequently misdiagnosed as squamous cell carcinoma. Differentiating between a lung primary and a metastatic disease has treatment implications and prognostic significance for the patient. When morphologic and immunophenotypic overlap exists, molecular testing can help distinguish mucoepidermoid carcinoma from other neoplasms.

Sinonasal leiomyosarcoma (LMS) is a rare and aggressive mesenchymal tumor with smooth muscle differentiation. The sinonasal tract is an unusual primary site for LMS, as scant smooth muscle exists in this location, with only 75 cases reported in the English literature including the case presented herein. Sinonasal LMS is considered an aggressive head and neck tumor with significant potential for recurrence and metastasis. Since recurrence is high and the potential for late metastasis exists, lifelong follow-up in these patients would be beneficial, especially among those with previous history of RB.

Background. Pulmonary alveolar microlithiasis (PAM) is a rare lung disease characterized by the deposition of calcium phosphate microliths or calcospherites, within the alveolar airspace. Typical imaging findings demonstrate a sandstorm appearance due to bilateral, interstitial sand-like micronodularities with basal predominance. Methods and Results. We describe an unusual case of a 48-year-old male with severe, familial PAM ultimately treated with a bilateral lung transplant. Conclusions. PAM is a rare lung disease caused by a mutation in the SLC34A2 gene, which encodes for a sodium-phosphate cotransporter in type II alveolar cells, leading to accumulation of intra-alveolar phosphate causing microlith formation. PAM has an indolent course but can progress to chronic hypoxic respiratory failure, ultimately requiring lung transplant, the only known effective treatment.

Cardiac myxoma is an uncommon benign mesenchymal neoplasm of the heart. It usually arises in the left atrium, near the valve of the fossa ovalis, and most frequently affects adults in the third through the sixth decades of life. It is hypothesized to arise from subendothelial vasoformative reserve cells or primitive cells that differentiate along the lines of the endothelium, but this remains speculative. Microscopically, the neoplastic cells are arranged individually, and nests, and are oriented in single or multiple layers around vascular channels. The neoplastic cells are immunoreactive for vimentin, calretinin, S100, nonspecific enolase, factor VIII, CD31, and CD34. The tumor can have diverse clinical presentations depending on its location and extent of disease and is predisposed to embolization. The current treatment is prompt surgical excision.

Medullary thyroid carcinoma (MTC) is a neuroendocrine tumor that is derived from C cells of the thyroid gland. It is a rare aggressive tumor, known to metastasize to lymph nodes, liver, bones, and lungs. A 41-year-old female, who presented with a breast mass, was initially diagnosed with invasive ductal carcinoma. She was also found to have a thyroid mass which was later diagnosed as MTC. On a rereview of the breast pathology, the morphologic features were strikingly similar to the MTC. Further investigation revealed that this was in fact a very rare case of MTC that had metastasized to the breast. We have identified 20 cases of MTC metastasizing to the breast in the literature that supports its occurrence as a real possibility. Albeit rare, medullary thyroid carcinoma should be considered in the differential diagnosis of a breast mass.

Human papillomavirus (HPV) in oropharyngeal squamous cell carcinoma (SCC) is a well‐known cause and prognostic indicator, and the utility of p16 as a surrogate marker for HPV status has been established. P16 and its relationship with HPV have not been defined in sinonasal malignancy nor has a link with outcomes been established. Patients with sinonasal SCC from 2011 to 2017 were identified from our pathology database. P16 immunohistochemistry and HPV RNA in situ hybridization were performed on tissue specimens. Forty‐seven patients were included. Disease‐free survival for p16+ patients was significantly higher than p16− patients (P = .043). Fewer HPV+ patients died (P = .052) or experienced recurrence (P = .0437). Odds ratio between p16 and HPV status was 14.19 (95% CI: 1.72, 442.03). Our findings demonstrate improved survival in both the p16+ and HPV+ groups and a positive association between p16 and HPV. There may be similar potential for modifying classification for HPV+ sinonasal SCC.

Plasma cell granulomas (PCGs) or inflammatory pseudotumors are nonneoplastic lesions that consist of predominantly antibody‐secreting plasma cells and innate immune cells such as neutrophils, macrophages, and eosinophils. Unlike in multiple myeloma, the plasma cells are polyclonal and present in a spindly fibroblast‐rich stromal background. These lesions mainly occur in the lungs; however, they can arise in other organs. PCGs from the gingiva are extremely rare, and a proper diagnosis is crucial to treat these patients further. These tumors have an increased number of plasma cells that are immunoreactive with CD138 and are polyclonal for kappa and lambda light chains, confirming these proliferations’ nonneoplastic nature. Surgical resection with clear margins, when possible, is the primary choice of treatment. Radiation and anti‐inflammatory steroid therapy are other therapeutic approaches. Critical and careful examination by a pathologist is necessary to rule out plasma cell neoplasms. Here, we report a rare occurrence of gingival PCG in an elderly male.

Background. The presence of two or more tumor entities growing in adjacent locations within the salivary gland is very rare, and pathologic studies on such lesions are limited, particularly those with molecular information. Since the clinical history and imaging studies are usually nonspecific, accurate diagnosis and clinical management largely depend on a thorough histological examination.Methods and Results. We describe a 71-year-old man with an unusual case of hybrid salivary gland tumor composed of mucoepidermoid carcinoma and basal cell adenoma. Molecular analysis revealed differing driver genetic alterations in each component.Conclusions. Hybrid salivary gland tumors are rare, and their pathogenesis is controversial. The combination of mucoepidermoid carcinoma and basal cell adenoma has not been previously described. While malignant transformation of adenoma to carcinoma seems plausible, gene sequencing was more suggestive of their independent derivation. Key to appropriate surgical management is identifying the more aggressive component, ideally at the time of intraoperative consultation.