"Concomitant" Cutaneous and Nodal Spitz Nevus/Tumor: A New Scenario for an Old Problem.

ABSTRACT: Spitz tumors are notoriously characterized by a high propensity to nodal involvement with a morphologically malignant (intraparenchymal) pattern but with little or no tendency toward further spread. We describe a case of spindle cell Spitz neoplasm removed from the thigh in a 34-year-old woman and initially diagnosed as "Spitzoid melanoma;" the sentinel node was characterized by a morphologically benign pattern of nodal involvement, with prevailingly capsular and septal aggregated of melanocytes showing the same cytomorphological features as the cutaneous tumor. Both the cutaneous and the nodal tumor were strongly ROS1-positive on immunohistochemistry; rearrangement of the ROS1 gene was confirmed with fluorescence in situ hybridization on the cutaneous tumor. The clonal relationship between the cutaneous and the nodal capsular/trabecular tumor, as established by their morphological and immunophenotypical resemblance, underlines the existence of a morphologically benign pattern of spread of Spitz neoplasms, as also suggested by the occurrence of eruptive Spitz nevi.

Technical note: double immunohistochemical stain (anti-CD31 and anti-cytokeratins) as a tool for a confident forensic post-mortem diagnosis of amniotic fluid embolism.

Amniotic fluid embolism (AFE) is a rare cause of unexpected late maternal gestational death. The forensic post-mortem diagnosis is rendered upon the histological recognition of fetal "foreign" material inside maternal lung vasculature. The authors propose a double immunohistochemical (anti-CD31 plus anti-cytokeratin AE1/AE3) stain in order to assess accurate amniotic fluid pulmonary embolic burden in a highly reproducible fashion based on the fact that such technique allows to detect an impressive amount of scales within lung vasculature, thereby offering further evidence that pulmonary embolic obstructive microangiopathy, rather than anaphylactoid reaction, is major determinant in AFE-related death.

Melanocytic and pseudomelanocytic nests coexist in interface dermatitis from head-neck sun-exposed skin: A report of three cases.

Discrete junctional cellular aggregates ("nests"), partially staining with melanocytic markers, are described in lichenoid tissue reaction, mainly from chronically sun-exposed skin. The concomitant epidermal flattening and papillary dermal fibrosis with melanophages, may raise the differential diagnosis to that of a regressing melanoma. We describe three cases of interface dermatitis of the head/neck area with clinicopathological features of melanotic discoid lupus erythematosus. These cases showed junctional aggregates, a few composed of inflammatory cells and colloid bodies ("pseudomelanocytic nests"), while others composed of S100- but MART-1+, MITF+, and SOX-10+ cells ("true melanocytic nests"); negativity of the melanocytic component for PRAME was a clue to benignity. True junctional melanocytic nesting may be induced by lichenoid dermatoses on chronically sun-damaged skin. The presence of colloid bodies and of the double negativity for S100 (within nests) and PRAME (both within nests and single melanocytes), together with clinicopathological correlation, avoids misdiagnosis.