Merkel Cell Carcinoma In Situ Arising in Association With an Infundibular Cyst With Unusual Reticulated Infundibulocystic Proliferation.

ABSTRACT: Merkel cell carcinoma (MCC) is an uncommon aggressive primary cutaneous neuroendocrine tumor usually arising on sun exposed skin of older patients. Most Merkel cell carcinomas are diagnosed as invasive tumors with only rare cases of MCC in situ (MCCIS) reported. MCCs are often associated with other cutaneous neoplasms and more recently have been described in association with cystic lesions, albeit rarely. We present a unique case of an 80-year-old male with a slow growing nodular lesion on the right buttock that on excision demonstrated MCCIS arising within an infundibular cyst with unusual reticulated infundibulocystic proliferation. The MCCIS was intimately associated with the infundibulocystic proliferation and demonstrated immunopositivity for CK20, CD56, AE1/AE3, synaptophysin, and Merkel cell polyoma virus. The confinement of the MCC to the epithelium together with the Merkel cell polyoma virus positivity further supports the assumption that viral positive MCC may derive from epithelial linage.

Aluminum granuloma in a child secondary to DTaP-IPV vaccination: A case report.

Reports detailing the acute formation of aluminum granulomas, which can cause persistent, intensely pruritic nodules secondary to the administration of aluminum-containing vaccines, are infrequently described in medical literature. To our knowledge, this is the first report describing the development of an aluminum granuloma causing a persistent, pruritic nodule at the injection site following the administration of the DTaP-IPV vaccine. We present the case of a 6-year-old girl who developed a severely pruritic subcutaneous nodule on her anterior right thigh at the injection site three weeks after the administration of the aluminum-containing DTaP-IPV (Kinrix) vaccine. The nodule was eventually excised 14 months after its initial appearance, after which her symptoms resolved. Histologic inspection demonstrated a dense, deep dermal and subcutaneous nodular mixed infiltrate of lymphocytes, histiocytes, and eosinophils, with germinal center formation. The bluish, amphophilic granular cytoplasm found in most of the histiocytes is a characteristic feature of "aluminum granulomas." This adverse reaction should be considered in any patient presenting with similar findings in the weeks following a DTaP-IPV vaccination or other aluminum-containing vaccines. Furthermore, the self-limiting tendency of these nodules should not preclude affected patients from any future vaccinations, though vaccines without aluminum should be preferentially selected when possible.

Locally aggressive and multifocal phosphaturic mesenchymal tumors: two unusual cases of tumor-induced osteomalacia.

Tumor-induced osteomalacia (TIO) has long been recognized as a clinical paraneoplastic syndrome. The identification of a unique histopathologic entity, the phosphaturic mesenchymal tumor (PMT), as a distinct etiology for TIO has been a more recent discovery. The majority of published cases describe a solitary, non-aggressive appearing soft tissue or osseous lesions in patients with osteomalacia; aggressive appearing or multifocal lesions appear to be exceedingly rare. These tumors characteristically secrete fibroblast growth factor 23 (FGF23). Elevated serum levels of FGF23 result in phosphate wasting and osteomalacia. In the majority of cases, laboratory abnormalities and clinical signs and symptoms of osteomalacia precede identification of the causative lesion by years. Following diagnosis, complete resection with wide margins to prevent local recurrence is most often curative. Imaging characteristics of PMT are diverse and remain incompletely defined, as the majority of previous publications are outside of the radiologic literature. We present multiple imaging modalities in two cases of patients with debilitating osteomalacia and unusual appearing PMTs: one with a locally aggressive lesion leading to pathologic fracture, the second presenting with exceedingly rare multifocal PMT.